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For parents trying to grasp the extent of their risk, and what they can do to minimize it. Also for parents looking back, trying to make sense of what happened.

Introduction

Questions and Answers

Bed Rest

Bed Rest Survival Tips

High Blood Pressure and Preeclampsia

Predicting the Birth Date

Diagnosing and Treating Preterm Labor

Are You in Preterm Labor?

Drugs for Preterm Labor

Cerclage

Diagnosing an Incompetent Cervix

Hidden Infections and Preterm Birth

If Your Water Breaks

If Your Water Breaks before Your Baby Has Reached Viability

When Baby Needs to Be Delivered Early

Checking on a Baby's Well-Being before He Is Born

Baby's Fighting Spirit

Steroids

Are There Medications other than Steroids

You Can Take to Help Your Baby?

Multiples

Likelihood of Prematurity

A Note If You Considered Multifetal Pregnancy Reduction

Twin to Twin Transfusion Syndrome

One Twin Needs Early Delivery

In Depth

Risk Factors for Prematurity:

Are You at Risk?

Introduction: In the Womb

A normal pregnancy that leads, nine months later, to the birth of a healthy baby is a natural life experience in which doctors are mostly watchful bystanders, until the time of delivery comes. But if you're at risk for a premature birth, your experience is going to be different. Some women will be aware of their risk before they conceive. For many others, suddenly becoming a patient comes as a shocking surprise.

If you're likely to have a preterm birth, you'll probably get assistance from an obstetrician who specializes in high-risk pregnancies (called a perinatologist). Your doctor's efforts will be directed at preventing a premature birth, or postponing it as much as is possible and advisable.

Why prematurity happens is still a puzzle. In fact, experts believe most preterm births result not from a single cause, but from several risk factors interacting throughout pregnancy. Doctors know many reasons for preterm birth (as you'll see from the list on page 33), and can identify many pregnancies at risk. But about half of the expectant mothers who go into preterm labor have no known risks for it. If you've already given birth to a preemie, and you never suspected that it might happen to you, you're certainly not alone.

Perhaps even more frustrating is that in many cases, premature birth cannot be prevented, even when mothers are known to be at risk. Still, even if a premature delivery cannot be avoided, a lot can be done to delay it for at least a few days (and sometimes much longer) -- enough time to take some precautions that can greatly reduce the health risks for both you and your baby. For example, you may be admitted to a hospital, where you and your baby can be monitored twenty-four hours a day, or transferred to a facility with more expertise in perinatology and newborn intensive care. If you have an infection, you'll be started on antibiotics, to help prevent your baby from getting it, too. And you may be given steroids to help your baby's organs mature faster before birth.

Sometimes, your doctor may decide to purposely deliver your baby before term, because he is not growing or doing well in the womb, or because it has become too dangerous for your own health to continue the pregnancy. About 20 percent of all preterm births are such so-called "elective," or medically indicated preterm births. The rest occur spontaneously -- about 30 percent after a woman's water breaks too early, and about half after preterm labor.

As you read through the information below, remember that only an experienced obstetrician can evaluate your own individual case. It's important for you to develop a good, trusting relationship with your obstetrician, so that you can count on her for support, as well as for state-of-the-art medical care, as you travel the demanding road of a high-risk pregnancy.

Questions and Answers

Bed Rest

My doctor told me to go on bed rest, but I have so many things in my life I need to do. Will bed rest really help prevent an early birth?

Nobody knows for sure. Bed rest is probably the oldest prescription for a high-risk pregnancy. Yet despite its widespread use -- one out of every five pregnant women in the United States is put on bed rest -- it has not been studied extensively. Although more research is needed before anyone can answer your question for sure, so far, the few studies that have been done have produced no convincing evidence that bed rest helps reduce preterm births.

So, why do almost all obstetricians prescribe it to women with preterm labor, premature rupture of membranes, preeclampsia, bleeding, or other pregnancy problems, and sometimes even as a preventive measure to women who are expecting multiples? Because even without proof, there are situations where bed rest makes sense to doctors, for some solid, scientific reasons.

For example, say your baby isn't growing as well as she should in the womb. Fetuses depend entirely on blood flowing through the placenta for their supply of nutrients and oxygen, and a mother's blood flow to the placenta is greatest when she is lying down. So, it makes sense that your baby will have the best chance of growing better if you spend a few extra hours in bed each day.

Or say your water has broken early. It makes sense that you could maximize the amount of fluid remaining around your baby by spending more time off your feet, since increased blood flow to the baby leads to greater production of amniotic fluid. Also, the fluid is less likely to drip out when you're lying down.

Bed rest also makes sense when gravity may be dangerous for a pregnancy. For example, once a woman's membranes have ruptured, there is a risk that the umbilical cord could slip down through her cervix -- an absolute emergency, because the cord could get caught there and squeezed, cutting off blood flow to the baby. Gravity also can be risky when a woman has a weak, or "incompetent," cervix, which could open if the fetus presses down on it too hard.

There is also good evidence that blood pressure is higher in women who are walking around. So, it is assumed that bed rest is helpful to pregnant women with preeclampsia, a condition involving high blood pressure which, when it's severe, can necessitate a premature delivery. Although research hasn't demonstrated so far whether bed rest itself makes the difference, we know there has been a dramatic improvement in the outcomes of pregnancies with pre-eclampsia. It may well have to do with the increasing use of hospitalization, which allows for both intensive monitoring and more bed rest than most women can get at home.

But if sometimes there is sound reasoning behind the prescription of bed rest, other times there is simply a mixture of observation and wishful thinking. Take preterm labor. Many doctors believe that women who remain active in the third trimester of pregnancy have more Braxton-Hicks contractions -- the normal, "false" labor contractions that don't lead to cervical change and delivery, and are of no concern. It's natural for obstetricians to extrapolate from that and assume that bed rest might reduce the risk of real labor, too. Nobody knows whether the initial observation itself, about Braxton-Hicks contractions, or the extension of it to real labor, is valid.

So far, studies on pregnant women haven't found that bed rest decreases preterm labor. (Monitoring contractions with a home monitor -- another intervention that seems like it should work -- doesn't appear to make a difference, either. Research suggests that home monitors don't improve pregnancy outcomes, although they do increase the number of doctor visits -- probably meaning they cause a lot of preterm labor scares.) But well-meaning obstetricians want to dosomethingfor women with preterm labor, so as long as there is a possibility that bed rest might help, many suggest it.

Some obstetricians also have observed that a prescription of bed rest can bring a helpful focus to a pregnancy. The thinking is that your pregnancy may have the best chance of succeeding if you, your family, and even your doctor focus more attention on your needs, concerns, and symptoms. Some women say this worked for them: that after trying to juggle a lot of things during the early part of their pregnancies, bed rest actually reduced their stress by allowing them to shift their emphasis away from their many other daily obligations.

Undoubtedly, obstetricians also prescribe bed rest partly as a holdover from past medical practice. As recently as a decade ago, nearly every woman with a pregnancy risk or problem was put immediately to bed, and told to stay there twenty-four hours a day.

Today, however, on top of a lack of proof of bed rest's effectiveness, there's a growing awareness of its potential costs. Total bed rest quickly causes bone and muscle loss (much of which is regained after a woman becomes active again). And for plenty of women it causes more stress, rather than less. In fact, it can be really hard on an entire family, especially when there are older children, or job and financial concerns. So, more and more doctors are recommending reduced activity -- lying down for a few hours each morning and a few hours each afternoon -- rather than complete bed rest, except in a few situations like an already open cervix, ruptured membranes, or severe preeclampsia.

Thankfully, you'll rarely see the once-common Trendelenburg position, in which a woman lies with her feet raised higher than her head. There's no evidence that it makes a difference, and a general consensus that no one can tolerate that position for long!

While you nestle in bed, try to stay as optimistic as possible (remember that medical treatments often work best when patients believe they will), and take a look at the practical tips below to make that experience more tolerable.

Bed Rest Survival Tips

OK. You've been put on bed rest, and you're feeling understandably miserable. How are you going to make it through the long weeks ahead? These survival tips may help:

• Recognize that you are performing a job, one of the hardest you'll ever do. If you are an active person with a tendency to ask "What have I gotten done?" each day, it's easy to feel frustrated and inadequate while on bed rest -- unless you give yourself credit for a daily achievement: an investment in your child's and family's future. Whenever you feel like you can't take it anymore, or are about to give in to the many temptations to get up, remind yourself of the job you have to do, and focus on your goal!
• Make your physical comfort a priority.Lying down for long stretches at a time can be very uncomfortable, and aches and pains are going to make your job far more difficult. You may have heard that you should lie on your left side, because blood flow to the placenta will be greatest -- but your right side is good for your baby, too. What's most important is simply to avoid lying flat on your back, because blood flow is reduced that way. Rest a pillow under one side of your tummy or back, so you're on a slight tilt. That's fine!
• Do light exercises in bed.To avoid muscle and bone loss, some obstetricians now arrange for a physical therapist to visit their patients on complete bed rest. If your doctor doesn't mention this, don't hesitate to ask. The therapist can teach you light, isometric exercises you can do while lying down. Or you can try to make up your own, very light exercise regime: point and flex your toes, do head rolls, rotate your hands, tense and relax the muscles of your arms and legs.
• Stay clean and attractive.It's amazing how this can affect your mood. Many hospitals have arrangements with hairdressers who will come to your room and expertly wash your hair without ever asking you to sit up. If you're at home, ask friends or the staff of your hair salon if they know of a hairdresser who makes house calls. Put on makeup every morning. Some women find that when they're feeling down, it lifts their mood to pamper themselves with manicures, pedicures, or facials.
• Make your environment attractive, too.It will just take a couple of minutes for a friend or your partner to tape up some family photos or art works by your children. When you're feeling imprisoned, warm touches go a long way!
• Don't expect the household to run as smoothly, or cleanly, as usual.It's a fact of life: women on bed rest don't have clean houses! If your family eats pizza for the seventh time in a week, you're not alone, either. The best thing is to lower your expectations, recognize that these things aren't a priority right now, and plan to fix them later, when you're up and about.
• Organize your space.It's terrible to have to ask for every little thing you need. Instead, ask your partner to put a table next to your bed, with the following items within easy reach: a telephone, books and magazines, grooming items, tissues, and disposable cleansing wipes (to wash your hands), the television remote control, paper and pencil, things you need for your hobby, a water pitcher, and a lunch that your partner sets out for you each morning. No matter how much your partner wants to help, it will minimize tension between you if he doesn't have to act as your constant gofer.
• Be understanding that bed rest is hard on your partner and children, too.Your partner's life is also disrupted. He may be as worried and distressed as you are, and he's probably picking up lots of extra tasks while holding down his usual responsibilities. Try not to be resentful of him for still being able to move around, or for not being able to meet your every need. And give him as much time off as you can. It's important to keep supporting each other.

  It's normal for your children to show some reaction, either behaving badly toward others or toward you. It's also normal for you to worry about them, and to think how long this period feels to them. But believe us, they will forget about it soon afterward. In the meantime, encourage them to spend time with you by making your bedside into a play area with their toys, and putting up a little table where they can eat some meals. Try to arrange special time for them with grandparents. Some mothers say it helped a lot for their child to be present when the doctor explained the need for bed rest; hearing it from an outside authority made the child understand better, and even eager to cooperate.

• If you were working, make sure to discuss financial arrangements with your employer.Find out if you are eligible for disability payments, and whether this time is being counted as part of your maternity leave or sick leave. Remember that the Family and Medical Leave Act requires employers with 50 or more employees to give up to 12 weeks of unpaid leave related to pregnancy problems or childbirth. You are eligible if you have been working for your employer for 12 months, and have worked at least 1,250 hours during the last year.
• Get some easy things done from bed.You haven't bought furniture or linens for the nursery yet? There are childcare books you wanted to read and don't have? Shop by catalog or computer. Or give your mother-in-law a list of all of the layette items you need -- she'll probably be thrilled to help, and it's like having a personal shopper!
• Don't be surprised if you get depressed, or have ups and downs.Many women say that some days their spirits are up, and then suddenly they find themselves in tears. Irritability, lots of anxiety, anger, and inability to concentrate are all normal reactions. You can expect a few naïve comments from friends, like "I'd love to be on bed rest and catch up on my reading." But most people who have been on bed rest themselves will tell you that it's hard. When you think what you're doing it for, though, it's worth it.

High Blood Pressure and Preeclampsia

I've always eaten right and exercised. But now, in my pregnancy, I suddenly have high blood pressure. I'm stunned.

Because high blood pressure is often associated with an "unhealthy" lifestyle, it can be a real shock for a health-conscious pregnant woman to find out that she has it. But there is a kind of high blood pressure that occurs only during pregnancy, and can strike out of the blue. When it is accompanied by other signs and symptoms, like protein in the urine and fluid retention (which shows up as very rapid weight gain, or a puffy face and hands -- not the normal leg swelling that many pregnant women have), doctors call it preeclampsia. Luckily, the prognosis is usually very good. Upward of 90% of all women who develop high blood pressure during pregnancy will deliver a healthy baby at term. And because preeclampsia always goes away after delivery, the vast majority of mothers are back to their previous state of health within a few days of their baby's birth.

Despite the fact that most people haven't heard of it, preeclampsia is actually quite common, affecting nearly 10% of pregnant women. Some women are more at risk for it: those who are pregnant with multiples, are overweight, already have high blood pressure, or have kidney disease or diabetes. Preeclampsia also runs in families, so if your mother or sister had it, the likelihood that you'll get it is increased. But an enormous 70% of women with preeclampsia don't have any risk factor for it at all.

Most of the time, preeclampsia is an easy diagnosis for your obstetrician to make. He'll measure your blood pressure, check your weight, and possibly do some simple urine and blood tests. But sometimes, it isn't clear whether preeclampsia or some other medical condition is causing the problem. It is important for your doctor to figure that out, because the cure for preeclampsia is delivery. If you have a severe case of it, a time may come when it's best to deliver your baby prematurely.

The reason preeclampsia is dangerous is that it causes changes in the body that are the opposite of what should happen during pregnancy. Normally during pregnancy, the amount of circulating blood in a woman's body increases, to provide for both her and her fetus, and her blood vessels open wider to accommodate it. But in preeclampsia, a mother's blood vessels tighten, and not as much blood can flow through them. Her blood pressure rises, and all of her organs, including her uterus, receive less blood.

When preeclampsia is mild, the amount of blood flow is slightly decreased but still adequate. But when preeclampsia is severe, a mother's vital organs may not get enough blood, and serious complications can result. Your doctor will watch you closely for kidney, liver, or intestinal problems (be sure to tell him if you have pain in your belly), and symptoms like blurry vision and headaches, which could indicate that your eyes or brain are suffering. In a very small minority of women with preeclampsia (only about 5%), the symptoms progress to seizures (called eclampsia) or dangerous abnormalities of blood clotting with liver damage (called HELLP syndrome, for hemolysis -- destruction of red blood cells -- elevated liver enzymes, low platelets). Women with these most severe forms of preeclampsia occasionally have strokes, or even die -- that's why your obstetrician takes it so seriously.

For a fetus, the main consequence of preeclampsia is receiving less blood flow through the placenta and, therefore, getting less oxygen and nutrients. For that reason, babies of mothers with preeclampsia are often small for their gestational age. (See page 70 for what that can mean for a child.) If the restriction of blood flow becomes extreme, or if the placenta separates from the wall of the uterus (a complication called placental abruption, which is more common in pregnant women with high blood pressure), there's a risk of fetal death. But thanks to alert doctors and good fetal monitoring, this is an uncommon tragedy today.

The earlier that preeclampsia occurs during pregnancy, and the more severe its symptoms, the more it can affect a mother's and fetus's well- being. Most women with mild preeclampsia continue their pregnancies until term, but women with severe preeclampsia usually deliver within a couple of weeks of being hospitalized for it. Some, however, are luckier, and are able to continue their pregnancies for much longer. Your doctor will tell you what you should expect in your own particular case.

The simplest and most commonly prescribed treatment for preeclampsia is rest, which can lower an expectant mother's blood pressure, and help her baby to get more blood flow. Your doctor may recommend bed rest at home, or admit you to the hospital. You may also get medications to lower your blood pressure, and to prevent seizures. The usual drug to prevent seizures is magnesium sulfate, which is generally safe for both mother and fetus, although it can have bothersome side effects (like making some mothers feel sick, and sometimes, temporarily depressing a newborn baby's breathing. Don't worry about that, though -- if necessary, a ventilator can help your baby breathe until the magnesium wears off).

If it looks like your pregnancy is becoming too risky to continue, your obstetrician will decide to deliver your baby prematurely. In fact, preeclampsia is the most common cause of elective preterm deliveries, done most often to protect the mother's health. When you hear that, you may think, "I don't care about myself, if it would help my baby to stay longer in my womb." It's heroic to be willing to take such risks for your child. But your family, including your baby, needs you. And when preeclampsia gets so severe in a mother, her fetus usually begins to suffer severely too, and is in real danger of dying soon in the womb.

Women who have had early, severe preeclampsia in a previous pregnancy have about a 40% chance of getting severe preeclampsia again. Unfortunately, efforts to prevent preeclampsia by using medications such as aspirin or calcium, on which researchers once pinned their hopes, have not been very successful. Although these drugs have not proved helpful when prescribed to a wide range of pregnant women, your obstetrician may still use them. They are safe, and there is some evidence to suggest that they may possibly be of benefit to women who are at the highest risk.

Predicting the Birth Date

My doctor says I'm at risk for having a premature baby. Is there any way of telling how long my pregnancy will last?

If pregnancy researchers had a Holy Grail, it would be the ability to predict whether an expectant mother would deliver her baby early, and if so, when. That crucial information would allow doctors to intervene early, when therapies are most effective, and only treat women who really need them. Tests of fetal well-being (see page 23) can help determine how long a pregnancy might last when there's a known medical complication. But those screenings can't predict whether preterm labor, or preterm rupture of the membranes, might cut short a pregnancy that is otherwise proceeding well.

Most methods adopted so far to help forecast the likelihood of a preterm birth -- such as adding up and scoring a mother's risk factors, or closely monitoring the opening of her cervix or her uterine contractions -- have had disappointing results. In recent years, though, researchers have been looking at a whole new set of tests that seem to be more useful and effective.

Many obstetricians have started using ultrasound, in addition to their traditional exam, of the cervix. Doctors traditionally examine a pregnant woman's cervix with their fingertips, to see if it is starting to open (or "dilate"). But this technique evaluates only the outer part of the cervix. Ultrasound can be used to look at the inner part of the cervix, where the earliest sign of dilation -- a shortening of its length -- can be detected.

An early answer as to whether the cervix is opening can provide a doctor with useful information. For example, if your cervix is shorter than it should be, your doctor may decide to give you a cerclage (a simple surgical procedure in which your cervix is sewn shut) to try to keep it from opening further. On the other hand, if you're having contractions, but your cervix looks normal on ultrasound, your doctor may decide that you're not in true labor, and instead of prescribing medication to stop contractions, may simply observe you for a while. Ultrasound measurement of cervical length is a quick and painless test that can be done at the same time as a routine vaginal exam.

One of the most exciting new tests for prematurity measures a pregnant woman's saliva for the presence of the hormone estriol: a kind of estrogen that has an important role in preparing the uterus for labor and delivery. One version, called SalEst (Sal for saliva, Est for estriol), has already been approved by the Food and Drug Administration. In the studies done so far, this test was used weekly to measure levels of salivary estriol in pregnant women at risk for premature birth. When a steep surge was detected, it indicated that labor was likely to occur in two to three weeks. When salivary estriol was low, labor in the following three weeks almost certainly would not occur.

Unfortunately, what seems like the perfect predictive test for prematurity has some limitations. One of them is that SalEst is more accurate in predicting when premature labor won't occur than when it will. This means that if your salivary estriol level is low, you almost certainly won't deliver soon -- valuable information that may save some women from being treated with bed rest or anti-labor drugs unnecessarily. But if your salivary estriol level is high, although you have an increased chance of delivering in the next several weeks, your pregnancy could well go on for much longer. Also, to date, SalEst has been approved only for singleton pregnancies, because hormone levels in multiple pregnancies follow different, more complex patterns. Moreover, some medications that may be given in a high-risk pregnancy (such as steroids) can affect a woman's estriol levels and limit the validity of the test.

Another marker for a possible early delivery is a protein called fetal fibronectin. Fibronectin helps to keep the placenta and the membranes well attached to the uterine lining. If free levels of this protein inside the uterus rise, it may indicate that the placenta and the membranes are getting loose. Many obstetricians now use fetal fibronectin testing to help predict a preterm delivery. If on a simple swab of the vagina or cervix, the level of fibronectin is low, it's very unlikely that you'll deliver within the next two weeks.

Other tests look for inflammatory substances in a pregnant woman's body to signal that a premature birth may be approaching. That's because some of the substances the body naturally produces to help combat infection or repair damaged tissues can also cause uterine contractions, loosening of the cervix, and weakening of the membranes, making them more prone to rupture. (Up to 25% of women who deliver prematurely have low-grade vaginal infections, and any damage to the placenta or umbilical cord, even if minor, can lead to inflammation.) One sign of infection or inflammation in the uterus is a protein called interleukin 6: if it is found in high levels in a mother's blood and in her amniotic fluid (which would require an amniocentesis to detect), it indicates that she may have a uterine infection, which could lead to preterm labor and delivery. But more studies are needed before doctors know exactly how to use "IL-6" as a routine test.

Your obstetrician will decide what tests to use to monitor your pregnancy, and when. None of the new tests is a panacea, and experts warn that they are more effective in predicting which women won't deliver prematurely than they are at picking out all of the women who will. But awareness of new risk factors and more effective ways to detect them, combined with more traditional tools, such as your obstetrician's knowledge of your medical history, physical examina- tions, and tests of your baby's well-being, can give your doctor a better perspective into your future.

Diagnosing and Treating Preterm Labor

I've been feeling some tightening in my stomach. Should my doctor treat me for preterm labor?

There's always a mixture of science and art in the practice of medicine, but when it comes to treating preterm labor, the balance tilts solidly to art. Your obstetrician has to make a judgment call as to whether you are having "true" labor or "false" labor. Some women just have unusually active uteruses, well before real labor starts. It's not always easy to tell whether your contractions are the real McCoy -- ones that will lead to cervical change and birth -- or just harmless ones whose only consequence is to give you and your doctor a dose of anxiety. That means that if you're having contractions, but your cervix hasn't begun to change yet, you may not need anti-labor drugs at all. On the other hand, you may be in the very early stages of real labor, when treatment has the very best chance of succeeding.

If real preterm labor is suspected, a mother is generally sent to the hospital, the safest place to be in case she is about to deliver. There, her contractions are monitored, along with her baby's heartbeat, to make sure the baby is not sick or in distress. She is put on bed rest and given intravenous fluids while her doctor tries to determine whether there's a treatable problem, like dehydration or infection, that is causing the contractions. About half the time, if preterm labor is not accompanied by bleeding or ruptured membranes (if your water hasn't broken yet), fluids and bed rest alone are enough to stop it.

If bed rest and fluids are not enough, and you and baby are doing well otherwise, the doctor will probably prescribe anti-labor drugs (which in medical parlance are called tocolytics) to relax your uterus and halt the contractions. Most of the time, these drugs put a quick stop to preterm labor in women who don't have bleeding, infection, or whose labor isn't already far along (whose water hasn't broken, and whose cervix is open less than four centimeters).

Whether or not labor will return (even if you continue taking medications), and what will happen during the rest of your pregnancy, is unpredictable. Having an episode of preterm labor doesn't necessarily mean you'll end up having a premature birth. Very often, the labor passes, the medication is stopped, and your uterus is quiet and calm again. Sometimes, the doctors never know why the preterm labor came and went -- whether it was an infection that flared up fleetingly, dehydration, or some other cause.

In other cases, preterm labor returns in a few days or at some later point in the pregnancy, and can result in a premature birth. If your preterm labor recurs while you are being weaned off the anti-labor medication, the first thing your doctor will do is reassess whether it is safe for you and your baby for the pregnancy to continue. If he thinks it is, he will restart anti-labor drugs, possibly switching you to one that can be taken orally, or that may have fewer side effects.

If this happens, you may be confused. Why do these medications seem to be working for you, when the studies say they only prolong pregnancy for a couple of days? That's a hard question for anyone to answer. It's possible that the drugs are making much less difference than it seems: that your contractions, scary as they are, are not the kind that would cause imminent delivery anyway, so your pregnancy would last just as long without the medication. It's also possible, since drugs can be more or less effective for different people, that they are helping your pregnancy more than average.

The two most commonly prescribed drugs to inhibit labor are magnesium sulfate and terbutaline. Of the two, magnesium is thought to have fewer serious side effects. But it must be given intravenously, so it is rarely used long-term. Many, although by no means all, women feel horrendous while they're on it, with symptoms like nausea, hot flashes, headaches, palpitations, paranoia, muscle weakness, and visual disturbances, among others. When a woman remains on magnesium for more than a few days, the symptoms sometimes ease up or go away. Your doctors will keep a close eye out for potentially dangerous complications such as pulmonary edema (a buildup of fluid in the lungs) or abnormal heart rhythms. With careful monitoring, these occur rarely.

Terbutaline can be administered by injections, pills, or a tiny pump that is implanted under the pregnant woman's skin. It's common for women to start with shots, and then, if they'll be staying on terbutaline long-term, to be switched to pills or the pump, both of which can be used at home. Some women tolerate terbutaline very well. But in others, terbutaline is associated with some of the same, unpleasant side effects as magnesium sulfate. The most common symptoms are palpitations, nausea, headaches, jitteriness, fever, and hallucinations. Doctors must also watch out for dangerous complications, including pulmonary edema, abnormal heart rhythms, and high blood sugar. Since serious complications occur more frequently from terbutaline than from magnesium, terbutaline is generally not prescribed to women with high blood pressure, heart disease, diabetes, or hyperthyroidism, who are at particular risk.

After two or three weeks on terbutaline pills, a woman's uterus can become less sensitive to them, and contractions can start up again. A break of a few days (during which you may take a different anti-labor drug) is needed before terbutaline can be effective again.

Obstetricians have other anti-labor medications they can use, such as indomethacin, nifedipine, or atosiban. All work somewhat differently, but have the same effect of relaxing the muscles of the uterus. Because their advantages and disadvantages are less well known than magnesium's and terbutaline's, you should ask your doctor for the latest information available.

Are You in Preterm Labor?

Just because you are having contractions before term, it doesn't necessarily mean that you are in preterm labor. Contractions throughout pregnancy are normal and expected, and are considered "false" labor unless they occur frequently (usually defined as more than once every ten minutes). Generally, real labor is accompanied by the thinning and opening of your cervix.What signs should you look for, to know if you are in preterm labor? As you read this list, keep in mind that many of these signs are present in perfectly normal pregnancies. You should call your doctor if their appearance represents a change for you:

• Uterine contractions, painful or not, that occur more than four times an hour.You may feel these as a tightening sensation in your belly. If you place your fingertips over your uterus when one is happening, it will feel firm. (If you think you are feeling some contractions, but they aren't that frequent yet, you can try drinking two or three large glasses of water and lying down for half an hour. Often, the contractions will gradually decrease in frequency.)
• A dull ache or sharp pain in your lower back.
• Menstrual-like cramps.
• Upset stomach-like cramps, possibly with gas pains or diarrhea.
• Pressure in your pelvis.
• An increased or changed vaginal discharge.(A blood-tinged discharge could mean the loss of the mucus plug that's like a stopper for the uterus. A greater than usual, clear leakage of fluid could be your water breaking.)

If you think you have any of these symptoms, or have any doubt, do not hesitate to call your doctor. Don't worry about being a pest. First of all, the people who worry about being pests rarely are. Also, you have obligations: to your doctor, who can't be with you all the time and counts on you to call with your concerns, and to your baby, whose well-being is at stake and who counts on you to represent him!

Drugs for Preterm Labor

I've been put on a drug to stop preterm labor, but I can't stand the awful way it makes me feel. Will it really make a difference?

No matter how stiff an upper lip you usually keep, the side effects from anti-labor medication can be hard to endure. Many women are lucky enough to be spared them, but others experience nausea, jitteriness, and other unpleasant symptoms that make them wonder whether the medication is really worth it.

For most women, anti-labor drugs make little difference in whether they deliver prematurely or not. Most studies suggest that the medications delay delivery for only two days, on average. But even a couple of days can be long enough to allow an expectant mother to get a course of prenatal steroids, which can boost her preemie's maturity and give him the best chance of doing well. That alone can be a real benefit.

Because of their side effects, and the inconvenience and questionable value of staying on anti-labor medications for long periods of time, some obstetricians won't prescribe these drugs to pregnant women for more than a week or so. But others, who believe that they may be beneficial in some circumstances for certain women -- especially those whose labor starts up again when the drugs are discontinued -- may prescribe them for longer.

If the medication you're taking is making you feel terrible, you should certainly talk to your doctor about whether you need to stay on it. He may have good reasons to believe that in your case, the drug is more effective than average, and that its benefits outweigh its risks. He may be able to prescribe another medication that will work for you, which won't bother you so much. Or he may reconsider, and agree that given your discomfort, it makes more sense to wean you off the medication now.

Cerclage

My doctor is recommending a cerclage. What is it, and what will it do?

A cerclage is a minor surgical procedure, usually done in the hospital by an obstetrician, in which the cervix -- the opening at the base of your uterus through which your baby emerges -- is temporarily sewn shut. Obstetricians recommend a cerclage when they conclude that a woman has a weak (or, in medical language, "incompetent") cervix. (What a word! Whoever thought your cervix would get a performance rating?) This means that instead of staying tightly closed until labor begins, the cervix tends to open at an earlier stage of pregnancy. Once the cervix has opened, the membranes of the amniotic sac can bulge out into the vagina, where they can become infected or rupture, leading to a miscarriage or a preterm birth. If you have an incompetent cervix, a cerclage could help prolong your pregnancy to a point when your baby, even if born before term, has a good chance of being fine.

Most of the time, a cerclage is a short and safe procedure, and a woman is in and out within a few hours. First you'll be given local anesthesia or light sedation. Then, your obstetrician will reach through your vagina, and sew four or five stitches around your cervix in a circle (in French, cercle), pulling them tight and knotting them to seal your cervix shut. The stitches are generally removed in your doctor's office when a preterm birth is no longer feared (at about 37 weeks of gestation). If you go into labor or develop an infection, however, the cerclage will be taken out earlier, in the hospital.

After a cerclage, most women are told to reduce their activity, or to remain in bed. You'll be advised not to have sexual intercourse, so as to avoid stimulating the cervix and to reduce the risk of infection (which is higher than normal with a cerclage in place). Periodically, your obstetrician will examine you, to look for changes in your cervix and for any signs of infection.

You may be wondering why your cervix may be "incompetent." The most common cause is an injury from a previous obstetric or gynecological procedure. For example, if you've had any surgery on your cervix it could have caused incompetence, as could a second trimester abortion. First trimester abortions done before 1973, with dilation techniques that have since been discontinued, also could damage the cervix. If your cervix tore during a previous, difficult vaginal delivery, you may have been left with some cervical incompetence. Some women may have an incompetent cervix because they were exposed, in their own mothers' wombs, to DES, a medication given to pregnant women in the 1950s and '60s to avoid miscarriage, which sometimes caused malformations in the reproductive organs of their fetuses. Often, however, the reasons for an incompetent cervix are unknown.

Obstetricians don't have reliable statistics on how likely a cerclage is to help you, because the research isn't definitive. The good news is that nowadays, 80% to 90% of women with classic signs of cervical incompetence who get a cerclage deliver a baby who survives, compared to only 13% to 38% of similar women who were pregnant in the past, before cerclages were done.

If a cerclage is put in early (before 18 weeks), it rarely causes any problems. Occasionally, after a cerclage is removed, there is some scar tissue left in the cervix that prevents it from opening fully during labor, causing the cervix to tear during delivery, or requiring a C-section. And if you go into labor and your cervix opens before your cerclage is taken out, the stitches could tear your cervix. But these are complications that your obstetrician can usually manage well. What probably matters most to you now is to bring your baby closer to term. A cerclage may help you reach that crucial goal.

Diagnosing an Incompetent Cervix

My last baby was born way too early. Now I'm pregnant again and my doctor thinks a cerclage will help. Why didn't they do that the last time?

In most cases, doctors can't diagnose cervical incompetence in advance. Most women have your experience: they are found to have a weak cervix only after it has already opened too early. To help diagnose an incompetent cervix ahead of time, some obstetricians are now using ultrasound to detect changes (shortening and thinning) which occur in the inner part of the cervix shortly before it begins to open. But ultrasound testing, like most medical tests, is not 100% reliable. The diagnosis of cervical incompetence is further complicated by the fact that small amounts of cervical dilation don't necessarily lead to preterm birth, so it's not always clear if it's worth the risk of doing a cerclage. Possible, if rare, complications of a cerclage are injury to the cervix, scar tissue left in the cervix, infection, and premature rupture of the membranes.

Even with hindsight, cervical incompetence can be difficult to determine. Doctors generally suspect an incompetent cervix if your cervix opened painlessly, without any preceding signs of preterm labor or infection. But sometimes, an infection of the exposed membranes, with preterm labor, is the first noticeable sign that a woman's cervix has been open. And a pregnant woman can have uterine contractions or an infection without being aware of them -- both of which can cause even a perfectly "competent" cervix to loosen and open up. Furthermore, many women who are diagnosed with cervical incompetence in one pregnancy won't have it again in another pregnancy. As a result, even with the best medical care, cerclages are given to some women who don't really need them, and are not given to all women who do.

Unfortunately, both a woman and her doctor may not know that her cervix is beginning to open. By the time they're aware of it, it's often too late to perform a cerclage. A cerclage is safe and effective only if you don't already have an infection or ruptured membranes (because the procedure could carry bacteria into your uterus, and make an infection more difficult to treat), if your cervix is not already dilated too much (there would be a high risk of damaging the exposed membranes of the amniotic sac, and infecting or rupturing them), and if you're not in labor (in which case it would be too risky, and not helpful anymore). The best time to do it is by 18 or 20 weeks of gestation, and before your cervix has opened. Most obstetricians, no matter what, would not perform a cerclage after 26 weeks of gestation, when the risks that the procedure itself could cause a preterm birth become very high.

So, there could be many possible reasons why you didn't get a cerclage in your last pregnancy. You can ask your doctor what factors were important in your particular case.

Hidden Infections and Preterm Birth

Do I really need to take medicine for an infection that doesn't bother me? If it isn't causing me any problems, how dangerous to my pregnancy could it be?

There's an increasing awareness that screening for and treating low-grade, often asymptomatic, infections in pregnant women may significantly reduce their risk of a preterm birth. It has long been known that some infections during pregnancy can cause a premature delivery, as well as congenital problems in the fetus. Substances that a mother's immune system produces as a reaction to infection can trigger changes in the uterus, cervix, and amniotic membranes that can lead to preterm labor. But obvious infections don't occur very often -- certainly not frequently enough to explain why the membranes of the amniotic sac are found to be infected at delivery in up to one-half of all preterm births, and up to 80% of births before 30 weeks of gestation.

Of course, simply finding an infection at the time of delivery doesn't tell you whether it came before, and maybe caused, preterm labor, or whether it came afterward. (During labor, when the cervix opens and the membranes of the amniotic sac rupture, some natural barriers to infection are removed.) But an abundance of new data indicates that hidden infections in expectant mothers' genital and urinary tracts may play a much bigger role than was ever thought in causing preterm births.

In an effort to figure out how important hidden infections were in causing preterm births, one of medical researchers' first targets was urinary tract infections. Bacteria in the urine are more common during pregnancy, and are often present without the symptoms of burning, itching, or fever that make an infection apparent. Many studies have now shown that the risk of delivering prematurely is much lower if pregnant women with asymptomatic urinary tract infections are treated with antibiotics.

More recently, researchers pointed their finger at a hidden infection called bacterial vaginosis, or "BV." BV is caused by an overgrowth of common bacteria that normally live in the vagina. According to some new findings, BV may double some women's risk of delivering prematurely. It is silently present in about 10% of Caucasian women and about 25% of African-American women. It is not a sexually transmitted disease, although women who become sexually active at an early age are more prone to it, as are those who douche (douching can destroy the useful bacteria of the vagina, which help to keep other bacteria under control).

Luckily, BV is easy to diagnose (your doctor painlessly swabs your vagina with something like a Q-tip), and it can be treated effectively with oral antibiotics. Several studies have shown that treating BV in women at high risk (mainly those who had a previous, unexplained preterm birth) can lower their risk for another preterm delivery by up to 70%. But in women who haven't had an unexplained preterm birth, it's not clear that having BV is harmful, or that treating it will help. There's even a small chance that treating it could hurt -- any time you take antibiotics, there's a small risk of an allergic reaction, or of developing an overgrowth of other bacteria that may be hard to treat. You can talk to your obstetrician about the pros and cons in your particular case.

Another hidden infection that is emerging as a possible cause of prematurity is gum disease. So don't be surprised if your dentist -- and your obstetrician -- tell you to floss to prevent prematurity, as well as cavities! If you've been diagnosed with gum disease, it is probably wise to get it treated by a dentist as soon as possible.

There are several other infections that can cause serious illness in a fetus, and occasionally lead to preterm birth, but which are sometimes so mild that a mother doesn't realize she has them. It will be your doctor's responsibility to decide if you need to be treated for any of these. Most obstetricians screen for sexually transmitted diseases like syphilis, gonorrhea, and chlamydia, and for viruses like hepatitis B, HIV, and rubella. Depending on your situation and exposures, your doctor may also add tests for other infections.

For most of these infections, prevention is the key: you'll be advised by your doctor to practice safe sex, not to eat raw or undercooked meat, fish, or shellfish, and not to touch dirty kitty litter (a great excuse to let your partner do that job!). You should try to stay away from anyone who's sick with something contagious. If you have Lyme disease in your area, try to follow even more carefully the precautions you already know: from late spring to early fall, whenever the temperature exceeds 40 degrees (when deer ticks are active), if you have to go near bushes or in the woods, wear light-colored clothes with a tight weave (to better spot ticks), socks over long pants, and long sleeves; keep long hair pulled back; spray tick repellent on your clothes (ask your obstetrician which product is safe for pregnant women); keep pets outside your house, or at least far from you, in a rug-free area that can be easily cleaned; and carefully check yourself for ticks every night. (If a tick is removed before it attaches to your skin, you will not become infected. If a tick is removed within 36 hours after it attaches to your skin, you have only a small chance of contracting Lyme disease: ask your doctor what to do next.)

Before your next pregnancy, if you haven't had rubella, mumps or chicken pox, you should get vaccinated for them. (These vaccines usually aren't given to women who are already pregnant, for fear they could harm the fetus.) You may have also heard about new vaccines for Lyme disease that are under investigation. It will be great news if these products are found to be safe and effective, but at this point it's too early to recommend them to a woman who is planning to get pregnant. Talk to your doctor about any recent developments, though.

If you had a preterm birth in the past, it may be tempting, but painful and probably useless, to go back and torture yourself about a hidden, undiscovered infection that may have been to blame for what happened. Even if you or your baby had signs of infection after delivery, there's no way to tell, in retrospect, if it was a cause or a consequence of your preterm labor. It is also impossible to know what would have happened if you had been diagnosed with an infection and treated with antibiotics during your pregnancy -- everything, or nothing, might have changed. Right now, if you can, try to focus on the present and future, putting your knowledge to good use, with the help of a trusted, expert obstetrician.

If Your Water Breaks

My water broke. Have we lost the battle?

Not necessarily. It's true that you may have to be in the hospital for a while, and it's likely that you'll deliver prematurely. But pregnancies often go on for some time after premature rupture of membranes (the medical term for water breaking), and it's quite possible that your baby will gain some additional, very valuable time in the womb.

It's understandable that you would feel scared at this point. There's something about the rush of fluid out of the womb that creates a feeling of great helplessness: there's nothing you can do to stop it while it happens, and nothing you can do to put it back. All you can do is wait and hope. One thing you should not do is blame yourself, or your partner, for what happened. We've known mothers who believed they brought it on by getting up from bed rest, and fathers who thought they were to blame for not carrying that last bag of groceries. In fact, nothing so simple has been found to be the cause of premature rupture of membranes.

Researchers don't have a full understanding of why some women's water breaks early, but most believe it's the culmination of a long-term process in which many medical factors combine. Women who smoke cigarettes are at increased risk, along with women who have had bleeding during the pregnancy, and those whose water broke before they went into labor in a previous pregnancy (at term or before). Uterine contractions, too much amniotic fluid, stress from the baby's growth, or the presence of more than one baby can all cause the membranes to weaken. Certain nutritional deficiencies may play a role. Experts suspect that infections (some without any symptoms) are often a key part of the story, with bacteria from a mother's genital tract climbing up through the cervix and irritating the membranes. Although it has been suspected that sexual intercourse might contribute to early rupture of membranes, studies have produced no clear evidence of that.

The first thing your doctor will want to do is to test the fluid that leaked out, to confirm that it was indeed amniotic fluid, rather than urine or vaginal secretions. Usually, when membranes rupture, there's a large gush of fluid, followed by a continuing trickle. In a few cases, though, women have some less dramatic dripping that goes on for a while. Once the doctor establishes that your water did break, he'll decide whether to deliver your baby right away or to wait.

Why shouldn't every pregnancy go on as long as possible? Because after membranes rupture, there are some real risks:

• Infection.The membranes that surround your baby act as a barrier to the bacteria that normally live in the vagina. When the membranes are broken, the bacteria can swim up into the uterus, infecting the mother, and possibly infecting the baby as well. A mother's infection can almost always be effectively treated, but for a fetus or newborn, an infection can be life-threatening, or cause long-term health and developmental problems. A premature baby who is born a little younger, but not infected, is often better off than an older preemie who is infected.

  Fortunately, less than 20% of fetuses become infected after premature rupture of membranes, and usually not until after their mothers have symptoms themselves, like fever or abdominal pain. So your obstetrician may not feel that it's necessary to deliver your baby unless you or your baby shows signs of infection.

• Inadequate growth of a fetus's lungs.Called pulmonary hypoplasia, its causes aren't fully known, but it is thought to occur because without much amniotic fluid, the uterus presses tightly against the fetus and prevents the lungs from expanding well. Lung expansion is one of the signals that prompts a fetus's lungs to grow and develop. (It's one reason fetuses, in the womb, practice breathing movements). There may also be growth hormones in amniotic fluid that are no longer getting into the fetus's lungs. No matter how old a baby is at birth, if her lungs are too small, it will be difficult, or impossible, for her to breathe.

  The risk that a baby's lungs won't grow large enough for her to survive outside the womb is greatest when a mother's water breaks early in the second trimester of pregnancy. The longer a baby is in the womb without much amniotic fluid, the greater the risk. The outlook is far better for a baby whose mother's water breaks after 26 weeks.

• A greater risk that the umbilical cord could slip into a dangerous position.This could cut off some oxygen and blood flow to the fetus.
• A baby's movements can be constrained.With little amniotic fluid to expand it, the uterus may press tightly against a fetus, constraining her movements. Lack of movement could cause her joints to become stiff and contracted, so that she can't bend or straighten some of them fully. Over time, these contractures may resolve, sometimes with the help of orthopedics or physical therapy.

You can see that these risks have to be balanced against the risks of your baby's prematurity, to come up with the right timing for delivery. In some situations, the decision is easy: as soon as there are obvious signs of infection or fetal distress, your baby will be delivered immediately. Before 32 to 34 weeks of gestation, in the absence of infection or fetal distress, most obstetricians believe that the risks of prematurity outweigh the risks of continuing the pregnancy. Most believe that the reverse is true once a baby reaches 34 weeks, when most preemies are practically as mature, if a bit smaller, than full-termers.

So how long can you expect your pregnancy to last? There's nothing more frustrating for parents to hear, but it is impossible to predict what nature will do in any, individual case. Occasionally, you're lucky, and the best possible outcome occurs: your membranes reseal within a few days, and amniotic fluid builds up again around your baby. No one knows why this sometimes happens, but when it does, the pregnancy can go on with nearly the same risks and benefits as if the membranes had never ruptured in the first place. Sometimes, the membranes partially reseal, leaving the door still open to infection, but providing the important advantage of an adequate amount of amniotic fluid around the fetus.

A majority of women give birth within a few days after their water breaks. But if labor doesn't occur within a few days, your pregnancy has a good chance of lasting considerably longer. Typically, pregnancies tend to last longer the earlier that membranes rupture. Some recent statistics from a small but heartening study reveal that women whose water broke between 14 and 19 weeks of gestation lasted a median of 72 days until delivery, while those between 20 and 25 weeks of gestation lasted a median of 12 days, and those between 26 and 28 weeks of gestation lasted a median of 10 days. Most women whose membranes rupture between 28 and 34 weeks of gestation, who were outside the scope of this study, give birth within a week.

Between now and delivery, you will most likely be kept in the hospital, where you and your baby can be monitored carefully, and taken care of if delivery occurs very quickly after labor starts. You will probably be kept on bed rest, partly to cut down on the amount of amniotic fluid that leaks out. Don't be alarmed, though, no matter what position you're in, if there is some continued leakage. Unless your membranes reseal, it's normal and unavoidable. Bed rest can also improve blood flow to the baby, which may help produce more amniotic fluid, and can lower the chance of the umbilical cord's falling into a dangerous position through the cervix. A few doctors occasionally use a technique called amnioinfusion (infusing fluid into the womb with a catheter), particularly to help a fetus tolerate labor, but the fluid tends to leak out so quickly that it doesn't seem to help with lung growth.

You will probably be given antibiotics to treat any infections you may have, and to prevent them in your baby. Antibiotics given after preterm rupture of membranes have been found to lengthen pregnancies and to give preemies a health advantage after birth. You may be given steroids to speed up your baby's maturation. You probably will not get anti-labor medications, which have not been proven to lengthen pregnancies after a woman's water breaks, and may mask signs of infection. You will need to abstain from sexual intercourse, which could introduce infection or bring on preterm labor.

To monitor for infection and fetal distress, your temperature and your baby's heartbeat will be checked several times a day. Your doctor may suggest an amniocentesis (taking a tiny bit of amniotic fluid out with a needle), if there's enough fluid left to do it safely. The fluid can be checked for infection, and can show how mature your baby's lungs are. You will probably get an ultrasound every few days, to observe your baby's breathing, heartbeat, and body movements, as well as to measure the amount of amniotic fluid.

One thing of which you can be sure: this period, when you have so little ability to predict or control the future, is going to be difficult for you and your partner. Taking one day at a time is the best strategy. Remember, every day you gain is valuable.

If Your Water Breaks before Your Baby Has Reached Viability

Sometimes, a woman's water breaks very early, before the baby would be ready to survive if she were born. If this happens to you before, say, 23 weeks of gestation, your doctor may present you with an excruciating decision. He may ask whether you want to try to go on with the pregnancy, or think it would be better to go through with delivery immediately. Choosing delivery now means that you know your baby will not survive. Choosing to go on means that you are willing to accept the risks that your baby may not thrive in the environment she's in, even if the pregnancy lasts much longer. Many babies who are born after extremely early rupture of membranes have poor outcomes, dying shortly after delivery, or suffering from short-term or long-term health problems, or even lasting disabilities.

Don't hesitate to ask your doctor for his recommendation, and for all of the information you need, such as: what gestational age range your baby is likely to reach by the time she is born, what the outcomes are like for babies in her situation (how great her chances of survival and living a healthy and normal life will be), and how much intensive medical care she is likely to need. When you read about general outcome statistics for babies born at various gestational ages on page 49, keep in mind that your baby is facing additional hurdles, such as lung hypoplasia , which can make her situation worse.

After weighing the facts, along with their deep feelings and beliefs, some parents conclude that the decision to deliver now, although incredibly painful, is the right one for them and their baby, given the risks ahead. Others want to try for more time. Either choice can be the right one for you and your family.

When Baby Needs to Be Delivered Early

My doctor says my baby isn't doing well in the womb, and he may decide to deliver him early. How does he know when the right time has come?

Few things are harder for an expectant mother than hearing that your baby would be better off being born prematurely than spending more time in your womb. Along with worrying about your baby's health and your own, you may feel inadequate, or betrayed by your own body. At a time when you should have been cheered by the tumbling presence of your baby inside you, instead you're undergoing checkups and tests -- observing him with trepidation and alarm.

It may help you to know that you're far from alone in this difficult experience. Elective, preterm deliveries -- done early for medical reasons -- bring nearly one-quarter of all preemies into the world. The most common reason for an elective preterm delivery is preeclampsia, which usually is done primarily to protect the health of the mother. But preeclampsia, and many other maternal medical conditions, also can adversely affect the health of a fetus. Sometimes, even when a mother is well, her uterus may not be the best environment for her baby.

These are the major reasons that an obstetrician might decide that the time has come -- sooner than expected -- when your baby would do better outside the womb:

• His growth has become very poor.If a baby isn't growing well in the womb, he may not be getting enough nutrients and oxygen, which can affect his long-term development. If your baby's growth is already slow, and it slows down even further or stops altogether, most obstetricians would decide that it's time to deliver him.
• He has signs of fetal distress.Fetal distress is a signal that a baby's supply of blood or oxygen is inadequate. It can be caused by problems with the placenta, anemia, an infection, or a severe illness of the mother or baby. Doctors recognize fetal distress when a baby moves a lot less, is unresponsive to stimulation, or has an abnormal heart rate. Obstetricians usually decide to deliver a baby urgently in that case, because fetal distress usually means that conditions in the womb are dangerous enough to jeopardize your baby's life or health right now.
• Congenital conditions.Babies with congenital conditions may sometimes do better if they get prompt medical or surgical treatment. If so, your doctor may opt for an elective preterm delivery.

Your doctors will assess how your baby is doing in the womb using one or more of the tests described in the box "Checking on a Baby's Well-Being Before He Is Born." To decide whether he would be better off if he were delivered now and cared for in a newborn intensive care unit, they'll take into account your baby's gestational age and size (crucial elements affecting how he will do after birth), and weigh the risks he'll face if he's born prematurely against the risks he faces by staying inside the womb. If your baby is still very immature and small, your doctor probably won't recommend delivering him unless he's facing life-threatening dangers. As he gets older, the risks of prematurity lessen.

You should know that there's always a good deal of guesswork in a decision like this. Unless you're past 34 weeks, when the major hurdles of prematurity are behind your baby, there's hardly ever a definitive "right" time for an elective premature delivery. Doctors usually discuss with parents the pros and cons of an elective preterm delivery, and try hard, using the tools and experience they have, to make the right choice.

Checking On A Baby's Well-Being Before He Is Born

There are various ways an obstetrician can "visit" a baby in his mother's womb, to find out how he's doing. Some are high-tech and may require a hospital visit. Others are simple ones you can do yourself at home. Depending on your particular medical situation, your obstetrician will decide when to monitor your baby's well-being, and which tests will be most helpful.

• Kick counts.This is the most basic kind of monitoring. It is based on the assumption that an active baby is a healthy baby. There are several different methods. A simple one is to lie down comfortably on your side once a day, and count how many times your baby kicks you. If you feel at least ten movements in two hours, that's good. (A fetus may be sleeping for 20 to 40 minutes, but then should wake up.) If you don't detect any movement, or your baby is moving much less than usual, you should immediately call your obstetrician. Some studies have shown that when expectant mothers do kick counts, they lower their risk of miscarriage or stillbirth.
• Ultrasound.Ultrasound uses sound waves to see inside your womb. An ultrasound scan is painless and completely safe for both you and your baby. Doctors use it to: estimate fetal weight and gestational age, and thereby determine if a baby is growing normally or not; check on how a baby's organs are developing; measure the amount of amniotic fluid (too much or too little fluid can indicate a problem); make sure the cervix is staying closed; assess whether the placenta is properly attached to the uterus; evaluate a baby's position and movement patterns.
• Fetal heart rate monitoring.You'll be asked to lie down, and a belt with a probe that detects when your uterus contracts will be wrapped around your belly. At the same time, an ultrasound probe, also on your belly, will monitor your baby's heart rate. The probes will be connected to a machine that continuously records your contractions and your baby's heart rate on a long strip of paper. Your doctors will assess whether your baby's heart rate is normal, and how it responds to contractions. This kind of monitoring is done routinely during labor, to detect any signs of fetal distress. A heart rate that is too slow or unchanging is worrisome, possibly signaling that the fetus is not getting enough oxygen. A heart rate that is too fast can be a sign of infection.
• Nonstress test.A nonstress test is performed the same way as fetal heart rate monitoring, but the doctors will be specifically watching to see that your baby's heart rate speeds up periodically. The human heart normally speeds up in response to various bodily functions, especially movement -- as when you dash to catch a bus, or when a fetus kicks -- thereby assuring that the body gets more oxygen and blood flow when it needs it. When doctors see that a fetus's heart rate speeds up periodically, they know that your baby is active, that his neurologic connections are intact, and that his heart is able to respond appropriately. If your baby's heart rate accelerates four or more times within a 20-minute period, the nonstress test is "reactive," and your baby is probably doing fine. If not, your doctor will probably want to do other, more specific tests. A nonstress test can last up to 40 minutes, because some babies may be peacefully sleeping and not move at all for some time. Some hospitals, to speed things up (and to spare you unnecessary worry) may try to wake up the little sleeper with a buzzing device, to get him finally to kick.
• Contraction stress test.This is also a kind of fetal heart rate monitoring. But unlike a nonstress test, which merely involves observing your baby, a stress test involves putting him in a stressful situation, to see how he reacts. That stressful experience is a uterine contraction, which has the power to temporarily decrease the blood flow through the placenta. If a baby is healthy, and everything is going well, he has a backup reserve of oxygen which allows him to sail through a contraction unscathed -- after all, that's what he'll have to go through during labor. But if that reserve doesn't exist, because there's already a scarcity of oxygen, his heart rate will slow down. To stimulate uterine contractions, you may be given a medication called pitocin, a manmade form of oxytocin, which can make your uterus contract, or be asked to gently rub your nipple, because that stimulates your body to release oxytocin naturally. If you're having spontaneous contractions (which may or may not be a sign of preterm labor, depending on their regularity and intensity), you may not need any medication or stimulation. For a stress test to be accurate, you'll need to have at least three contractions within a 10-minute span, each one lasting at least 40 seconds. To achieve that, the test may last for up to two hours. Since uterine contractions can be the enemy for some mothers -- those with preterm labor or vaginal bleeding, for example -- a stress test may not be advisable for them. An excellent alternative to a stress test is a biophysical profile.
• Biophysical profile.This is a multifaceted exam in which your baby's behavior is observed with ultrasound for 30 minutes. The doctor will score your baby on five elements:
  • Breathing.A healthy fetus will make breathing movements for at least 30 seconds.
  • Body movements.A healthy fetus will move his body or limbs at least three times.
  • Tone.A healthy fetus will have at least one episode of extending his limbs or trunk, and then returning to a flexed position (such as opening and closing his hand).
  • Heart rate acceleration.A nonstress test should be reactive, or the examiner should see by ultrasound that your baby's heartbeat speeds up at least twice in 30 minutes, when he moves.
  • Amniotic fluid volume.The amount of amniotic fluid around your baby should be normal.

• Doppler studies.Using ultrasound, doctors can measure the blood flow in the umbilical cord, and pick up problems in the circulation between a mother and her fetus. Doppler flow studies can be helpful in determining when the placenta is not functioning adequately. But because the results are not always accurate, they're not universally performed, and your doctor will have to use his judgment in interpreting them.
• Percutaneous umbilical blood sampling (PUBS).This test involves taking a sample of your baby's blood from the umbilical cord. It is more risky than most other fetal diagnostic tests (because the cord could be damaged), and obstetricians do it only when they need very precise information about your baby that can be obtained in no other way. You will be given local anesthesia, and a long needle will be inserted in your belly. Your doctor will watch exactly where it's going with ultrasound, as she guides it through your uterus and into a blood vessel in the umbilical cord. PUBS may be used to evaluate your baby's blood counts, if there's reason to believe they may be abnormal, or to see if he has an infection or genetic problem that could explain why he's small for his gestational age. Normal results could confirm that your baby is doing well in your womb, perhaps allowing you to avoid an elective preterm delivery.
• Amniocentesis.You may already know that amniocentesis is offered to many women as a test for some birth defects (like Down syndrome). But amniocentesis -- which involves taking a sample of amniotic fluid by passing a needle through your belly and into your uterus -- has other useful applications, as well. In cases of preterm labor or premature rupture of the membranes, amniocentesis can detect a uterine infection sooner than maternal blood tests and other cultures. If your amniotic fluid were infected, it would probably convince the doctors to do an elective delivery. Moreover, the same amniotic fluid can be used to assess your baby's lung maturity. When a fetus's lungs have developed enough to breathe well on their own, certain substances are released into the amniotic fluid. If your baby will be delivered soon, and those substances aren't present, you'll probably be given steroids to speed up the maturation of your baby's lungs. If, instead, your baby's amniotic fluid says "lungs OK," your doctor may opt for an immediate delivery.
• Tests to predict an imminent delivery.Tests of hormones in your saliva, or a substance called fibronectin in your uterine and vaginal secretions, can be used to monitor whether your uterus is already preparing for labor (see page 10). If these tests are positive, it indicates that you may deliver your baby soon -- within the next two weeks. Your doctor may use one or more of these tests to decide whether to treat you with steroids (to boost your baby's maturation in preparation for an early delivery), whether or not to keep you in the hospital or on the labor ward, or whether to go ahead with a delivery that may happen very soon anyway.

Baby's Fighting Spirit

My baby kicks a lot. Does that mean he is a fighter?

Some fetuses, with a constant stream of left hooks and right jabs, give their mothers the distinct impression that they have a future as heavyweight boxers. Others seem a lot more relaxed, moving more softly and fluidly, or, it sometimes seems, not that much at all.

There's no doubt that different fetuses have different movement patterns, but nobody knows whether they foretell who will be "fighters," those able to face down the challenges and hurdles of prematurity with particular vigor. First of all, strong children (physically and emotionally) come in many different packages: strong, silent types; feisty, impish types; or assertively physical types. In addition, at this point researchers don't even know whether movement patterns established in the womb persist into infancy and childhood. Plenty of parents are surprised to see their in utero prizefighter turn into an easy, calm baby -- and vice versa. Many factors can affect fetal movements, including a mother's diet, mood, and activity level (when mothers are busier, they tend to concentrate less on their babies' movements and think they're moving less, even when they're not), the time of day (fetuses sleep sometimes, too), and the stage in pregnancy (as fetuses grow and have less room to move around, their movements tend to involve more wriggles and fewer kicks), along with the baby's own physical strength and character.

It's safe to say that whatever is going on in your belly now, you will be amazed by your tiny baby's spunk and spirit. Almost all parents of preemies are. In the nursery, you see one fighter after another after another. To adults, it is inspiring. To babies, it just seems to come naturally.

Steroids

My doctor is giving me a medication to make my baby's lungs mature more quickly, because she may be born any day now. How much difference will it make?

You've probably been told that every extra week, in fact every extra day, in the womb is valuable, allowing your baby's organs to mature just that much more, so they'll have a better chance of functioning well when the moment comes that she enters the world. Luckily, we live in an era when modern medicine can sometimes fill in for nature, at least partially, when nature isn't cooperating. Studies show that when a mother takes steroids at least twenty-four hours before delivery, her premature baby's lungs mature faster, giving them the equivalent of about an extra week in the womb.

Steroids are hormones that everyone's body produces, especially during periods of stress. These hormones surge, naturally, in pregnant women just before delivery, speeding up maturation of the fetus's organ systems -- a kind of developmental boost just before they have to function independently.

Getting steroids can be incredibly valuable to a preemie. One of the most common illnesses in the intensive care nursery is respiratory distress syndrome, or RDS, which arises from lung immaturity. A baby with RDS is dependent on a ventilator or other breathing assistance, and at risk for other, potentially serious complications, until her lungs are able to breathe well on their own. The risk that a newborn will have RDS drops lower and lower with increased gestational age at birth. While virtually all preemies born before 26 weeks of gestational age have to deal with respiratory distress syndrome, only about a quarter of 30 to 34 weekers, with their more mature lungs, do.

When steroids are given before delivery to their mothers, newborn preemies between the ages of 28 weeks and 34 weeks of gestation have a dramatically reduced rate of RDS. For infants born before 28 weeks, it's not clear that the incidence of RDS is reduced, but the severity of the illness may be. Beyond 34 weeks, the risk of RDS is so low that a mother won't get steroids unless her fetus's lungs are known to be especially immature. Besides helping to prevent respiratory distress syndrome, steroids also speed up maturation of the brain and the intestines, lowering the rate of intraventricular hemorrhage (bleeding in the brain), and NEC (inflammation of the intestines), some of the most worrisome, potential health consequences of prematurity.

If your doctor is giving you a steroid called betamethasone, you'll get two shots, twenty-four hours apart, and if he's giving you one called dexamethasone, you'll get four shots, twelve hours apart. The maximum benefit comes when you get a complete course at least twenty-four hours before you give birth, although there's some benefit even if there is less than twenty-four hours before delivery. The effects last for seven days or more. If more than a week passes and you haven't yet given birth (which is good news!), you may be given another course. Most doctors would not give any more than that, however, because too many courses of prenatal steroids may adversely affect the long-term growth of a baby's brain, and possibly other organs, offsetting some of the future potential to help them in the short term.

What about other risks from the way that prenatal steroids are being used? Some mothers have medical conditions, such as diabetes, which steroids can worsen. Your obstetrician will judge whether taking steroids is safe for you. The fear that a course of steroids before delivery would increase a mother's risk of getting an infection, or have some negative short-term or long-term effects on her baby, has been extensively researched, including follow-up of preemies until they were twelve years old. Thankfully, studies haven't shown any adverse effects from one course of these extraordinarily valuable drugs.

Are There Medications other than Steroids You Can Take to Help Your Baby?

Researchers are always on the lookout for medications that a mother can take before a premature birth, to help her baby mature faster or to prevent some of the complications of prematurity. Various drugs have been studied because they looked promising, but none other than steroids, as yet, have been proven effective.

For example, it was hoped that giving magnesium sulfate (a medication prescribed for preeclampsia and preterm labor) to mothers of preemies might help to prevent cerebral palsy. So far, research has come up with no solid evidence to support this. There's been speculation that phenobarbital and vitamin K, given to a mother before delivery, might reduce the risk of bleeding and damage in her premature infant's brain. As of now, the evidence isn't there, either, although a few obstetricians do prescribe these to their patients. Other possibilities have been investigated, and will continue to be, with the hope that one day, some will be successful.

Multiples

Likelihood of Prematurity

I'm pregnant after an IVF cycle, and I'm having more than one! Am I likely to deliver prematurely?

You may know that if you're pregnant with more than one fetus, you have a higher chance of a preterm birth. That risk increases with the number of babies you're carrying. Most couples who undergo infertility treatments are told about that risk, but it's easy to be so focused on just getting pregnant that you put the possibility of having more than one baby into the back of your mind. Secretly, a couple might even hope for twins or triplets, to see their desire for a big family finally come true, all at once, while they have the chance.

But although a multiple gestation is sometimes an unavoidable consequence of infertility treatments, it's not usually a desirable one, especially when more than twins are involved. Multiple pregnancies have higher rates of miscarriage, stillbirth, and prematurity. A preterm delivery is much more likely for one simple reason: the amount of space in the womb. When the human uterus, which was not meant to carry more than one fetus, gets very distended, it tends to contract. That may be nature's way of trying to deliver a baby when it's well grown; but not surprisingly, with multiple fetuses the womb gets overcrowded and tends to contract before term. Also, because of the space and nutritional resources they have to share, multiples tend to be smaller than singletons after a certain gestational age.

Women who are pregnant with multiples are more subject to pregnancy complications, like bleeding or high blood pressure, which also can lead to an early birth. To top it off, recent research suggests that women who had fertility treatments tend to give birth two to three weeks earlier than women who did not have fertility problems, when carrying the same number of babies. There may be a relationship between prematurity and infertility treatments, or prematurity and infertility itself.

Putting all of this together, a normal, singleton pregnancy lasts about 40 weeks, on average, while the average length of a twin gestation is about 36 to 37 weeks, and each additional fetus shortens it by about three and a half weeks. The likelihood of a preterm birth is only about 10% in a singleton pregnancy, but goes up to nearly 50% for a twin gestation, and nearly 90% for triplets and up.

There's a bright side to this, though. As you can read on page 51, the outcome for preemies born at 34 or more weeks of gestation, which would include most twins, is almost identical to that of babies born at term. Preemies born at 32 or 33 weeks, the average age for triplets, usually do very well. Plus, some studies suggest that multiples may be even better equipped than singletons to overcome some hurdles of prematurity -- and that advantage increases with the number of babies in the womb. This means that a triplet may have a slightly better chance of survival than a twin born at the same gestational age and weight, and a twin may have a better chance than a singleton. Unfortunately, when a newborn is tiny and very immature, the small payoff of being a multiple may not improve his chances all that much. Still, it's something!

A Note If You Considered Multifetal Pregnancy Reduction

You may have been told by your obstetrician, early in your pregnancy, about the possibility of a multifetal pregnancy reduction. This procedure, in which one or more fetuses are aborted on purpose, is done to give the babies who will later develop a better chance to survive, so they can reach an age when they can be born without such very high risks of an early death and future disabilities.

Couples who were faced with this choice, no matter what decision they made, may feel comfortable that they did the right thing, or may be left with deep sorrow and excruciating doubt. It's important to remember that, for this particular path, there is no absolutely right or wrong choice. Even the future cannot prove that your decision was good or bad, because not even time can tell you what would have happened if you had chosen differently. Try not to let your joy for the lives that are developing in your womb be shadowed by past choices or future statistics. Give yourself credit that whatever happens, you've done what was in your power, or what your conscience allowed, to best help your babies and your family.

Twin to Twin Transfusion Syndrome

My doctor said my twins aren't doing well in my womb because they share a blood vessel. What problems will they have, and can anything be done to help?

Your doctor probably suspects a condition called twin to twin transfusion syndrome, which can affect the health and growth of identical twins during pregnancy. A twin to twin "transfusion" occurs when shared blood vessels in the placenta cause too much blood to circulate out of one twin and into the other.

To understand how this can happen, it's necessary to look at events occurring at the very beginning of life. A fertilized egg, in order to develop into a fetus, needs a placenta to supply it with vital amounts of oxygen and nutrients from the mother's blood, and to get rid of its waste. The placenta begins to form right out of the fertilized egg, the moment it attaches to the uterus, quickly growing into a net of fetal blood vessels connected to the fetus by the umbilical cord. Around the fetus, a sac of membranes -- the amniotic sac -- forms, and gradually fills with amniotic fluid, made mostly of fetal urine.

What about twins? Fraternal twins come from two different eggs, and always have two separate placentas and amniotic sacs. Identical twins come from the same egg, which splits sometime after fertilization, forming two fetuses. When that split happens very early after fertilization, before the placenta has developed, each identical twin will make its own placenta and amniotic sac. But when the split happens later, after the placenta has already formed, the twins will share the same placenta. Depending on whether the fertilized egg splits in two before or after the amniotic sac forms, each twin may make its own sac, or they may share one.

In a placenta shared by identical twins, there are almost always some blood vessels connected to both umbilical cords, which allow the circulation of a little blood from one twin to the other. As long as the blood vessels are small, and the amount of blood flowing from one to the other is minor, it's not a problem. But if the connection involves major blood vessels, a substantial amount of blood may flow from the first twin (the donor) into the other (the recipient).

The recipient twin gets more blood, with its oxygen and nutrients, so becomes bigger. But a lot of blood can be too much of a good thing, and bigger is not always stronger. The recipient twin can get overloaded with fluid, putting a strain on her heart to pump all that blood. When twin to twin transfusion syndrome is really severe, the recipient twin is at risk of dying in the womb or in early infancy of heart failure. The extra blood will also make her urinate a lot, filling her sac with excessive amounts of amniotic fluid. Polyhydramnios is a main cause of spontaneous preterm labor.

The donor twin can also get into trouble. She gets less blood than she should, so lacks some oxygen and nutrients. This can restrict her growth, making her smaller than the other twin. She won't urinate as much, so there may be too little amniotic fluid in her sac (a condition called oligohydramnios, see page 35). Not having enough amniotic fluid increases the risk that the umbilical cord can get compressed in the uterus, leading to a dangerous interruption of blood flow to the fetus. In severe twin to twin transfusion syndrome, the donor twin is also at risk for heart failure, from profound anemia.

It's hard to generalize about the effects of this condition. If it's mild, both babies will probably do well, perhaps differing in size, or blood cell counts, but with few or no other consequences. If it's moderate, an early delivery and prematurity are its likely consequences. But if it's severe, the disturbances in blood flow can potentially damage the vital organs of both fetuses, leading to death, or to long-term disabilities if they survive.

Twin to twin transfusion syndrome is usually diagnosed by ultrasound, in the second trimester of pregnancy. Indicators are: a shared placenta, a difference in your twins' size by 20% or more, and too much fluid in the bigger twin's sac with too little fluid in the smaller twin's sac. Sometimes ultrasound measurements of fetal blood flow can pick up different circulation patterns in the twins, and show the blood vessels that are causing the problem.

Traditional treatments for twin to twin transfusion syndrome have not been very effective. Some obstetricians consider it useful to drain amniotic fluid from the sac of the receiving twin, because it has been suggested that this may sometimes slow down the passage of blood from one twin to the other. This procedure has to be repeated often, though, and other doctors don't think it works. Drugs may be given to the mother to help the babies' hearts, or to reduce their urine output (so the recipient twin won't make as much amniotic fluid), but they are not without risks. Once the obstetrician thinks that the babies' problems in the womb are worse than the possible complications of being born prematurely, an elective preterm delivery is commonly done.

A recent innovation -- still experimental -- is laser surgery on the placenta. This involves closing the blood vessels connecting one twin to the other while both babies are still in the womb, then going on with the pregnancy. So far, this procedure is only being done in a few hospitals in the United States and Europe. It carries a high risk of losing one or both twins, and there are some risks to the mother, but some doctors think it is promising.

One Twin Needs Early Delivery

One of my twins is having trouble in the womb, and the doctor says she'd benefit from an early delivery. But the other is doing fine, and could go to full-term. Whom should I put first?

The dilemma that arises when one of your babies is doing well during pregnancy, and the other is not, can be gut wrenching. While your womb is the best possible place for one of your twins, for the other it's dangerous, leading your doctor to believe that she would be better off being born prematurely, and cared for in an intensive care nursery. Doctors often want parents' input in deciding what's best: to deliver both twins now, before term, or both twins later -- a decision that requires parents to help one of their babies at the expense of the other.

If you are faced with a painful decision like this, the first thing you need is information. It's important for you to understand, as clearly as possible, the risks and benefits of each course of action for each of your children. For your baby who is doing fine now and may abruptly become a preemie, you can read about a premature baby's prospects for survival and long-term health.

For your baby who is not doing well now, the best thing is to discuss her risks and prospects with your obstetrician, since she may have medical problems that make the statistics different for her than for the average baby, whether she stays in the womb or not.

Unfortunately, even when you've armed yourself with all of the information that's available, there is rarely an obvious "right" answer. If one choice is clearly better in balancing the welfare of both of your children, your obstetrician will direct you that way. Very rarely, the problem can be solved with a delayed interval birth (see page 66), in which one baby is delivered days or weeks before the other, but this requires that certain conditions be met, and is never a sure bet.

The only way that most parents can make a decision like this is to follow their values and their hearts. Some parents naturally want to protect their child who is most sick or vulnerable, and feel compelled to do whatever will help her. Others feel that it is their job as parents not to hurt their children who are thriving. So, for example, if one of their children is fine while the other will face daunting survival or developmental risks no matter what, they would not make a choice that would hurt their healthiest baby's chances. Some parents lean toward accepting the most natural course of events, believing that as long as the pregnancy would keep going on its own, they and the doctors should not intervene to stop it.

You will probably second-guess your decision many times over the coming months and years, no matter how things turn out. Just remember that the very nature and essence of a family is that several people are in it together. As parents, it's impossible for us to do what's best for every one of our children all of the time -- much as we wish we could. We are forced to weigh everyone's needs, and to make decisions that are best for one member of the family in one situation, for another in another situation, always thinking about what's good for the family as a whole.

Take all the time you can to think and talk through your decision. Later, give yourself credit for trying to make the best choice for your family that you could, in an exceedingly difficult situation.

Risk Factors For Prematurity: Are You at Risk?

While you can learn from this list about some of the things that increase the odds of giving birth early, try not to use it to draw conclusions about your pregnancy or anyone else's you love. That would be a mistake, because in any pregnancy, the medical issues may be more complex than what you can read in here. Many women who have a risk factor on this list still give birth at or near full-term. Risk factors for prematurity may be weak or strong, and they often interact. Remember that only your doctor can adequately evaluate your own, individual case and make an accurate prognosis for your pregnancy and your baby.

Some Common Causes of Preterm Birth

Obstetric history

• Previous premature delivery.This is one of the most important risks for a premature birth. If you've already had a premature baby, you have a 20% to 40% chance of seeing it happen again.
• Previous second trimester abortion.Women who have had a second trimester abortion have a higher risk for preterm birth, because that surgical procedure requires a wide dilation of the cervix, which can damage it and lead to cervical incompetence. A single, first trimester abortion doesn't increase the risk for delivering prematurely, but having several first trimester abortions may.
• Becoming pregnant less than six months after a previous delivery.Your body may not be fully recovered and prepared to handle another pregnancy so soon.
• Infertility.Women who have had a lot of trouble conceiving, including those who become pregnant while receiving treatment for infertility, have a higher incidence of preterm delivery, for reasons that are not yet clear.

Problems with the reproductive organs

• Malformations of the uterus.If you have fibroids, or a uterus with an abnormal shape, you have a higher risk for having a smaller than normal baby, and for delivering prematurely. That's because there may not be enough room in your womb for a baby to grow to full-term size. Many problems with the uterus can be corrected with surgery, after which you may have a much better chance of carrying a pregnancy to term.
• Cervical incompetence.Some women have what's called an "incompetent cervix": their cervix (the opening of the womb) tends to open too early in the pregnancy, causing premature birth. You can have an incompetent cervix for unknown reasons, as a result of previous gynecologic or obstetric procedures, or from exposure when you yourself were a fetus in your mother's womb to a medication called DES, which was given to women in the 1950s and '60s to prevent miscarriages. A simple surgical procedure called a cerclage can be done during pregnancy, to try to keep your cervix closed until term.

Obstetric complications during this pregnancy

• Multiple gestation.Twins have a 25% to 50% chance of being born before term, and that rate rises with each additional fetus. The main reason is purely mechanical: the uterus gets distended by all of the babies inside, and distention is a signal for it to contract. But some multiples are born prematurely for other reasons, such as high blood pressure or breathing difficulties in the mother, or because the fetuses aren't growing well in the womb.
• Bleeding in the second or third trimester of pregnancy.The most common causes are two conditions of the placenta: placental abruption and placenta previa. Both are common causes of elective, preterm delivery. They can be harmful to the mother, who can lose a lot of blood, and to the baby, because anything that interferes with good functioning of the placenta (which provides the fetus with oxygen and nutrients) can interfere with a baby's development.

  Placental abruption means that a part of the placenta has detached from the wall of the uterus. When that happens, the detached part of the placenta is no longer able to get oxygen and nutrients from the mother's blood. The most common symptoms you would notice are vaginal bleeding and abdominal pain. If the area of abruption is large, it can be very dangerous, seriously disturbing the blood and oxygen supply to the fetus, and may require an emergency, preterm delivery. But if the area of abruption is small, and the rest of the placenta is working well, it won't make much difference for the growth and well-being of the fetus, and your pregnancy can continue. Ultrasound and other tests of fetal well-being can usually assess the damage.

  Placenta previa means that the placenta partly or completely covers the cervix, so that when your cervix dilates, or the fetus pushes against it during labor, it can tear and bleed. Bleeding may also occur as pregnancy advances, and the lower part of the uterus stretches. The usual reason for a premature delivery for a placenta previa is to prevent a serious maternal hemorrhage.

• Polyhydramnios or oligohydramnios.Polyhydramnios means there's too much amniotic fluid. The excess fluid can overly distend the uterus, leading to early contractions and preterm delivery. Since the fetus normally swallows large amounts of amniotic fluid, anything that impairs the fetus's ability to swallow (such as problems with his mouth, neck, or stomach, or neurologic conditions) can cause too much amniotic fluid to build up. A variety of other maternal and fetal conditions are associated with polyhydramnios, and your doctor will discuss any with you that apply. Sometimes, no reason for the extra fluid is found. If your case is severe, your doctor may drain some of the fluid out with a needle and syringe, in a procedure similar to an amniocentesis, to lower the immediate risk of preterm labor and delivery.

  Oligohydramnios means there's too little amniotic fluid. This can be caused by premature rupture of the membranes (when your water breaks, most of the amniotic fluid leaks out), abnormalities of your baby's urinary system (because the amniotic fluid is mostly made of fetal urine), or a poorly functioning placenta (babies who get less blood flow through the placenta will urinate less). Often, oligohydramnios is accompanied by signs of fetal distress, because your baby is no longer protected by an intact, fluid-filled sac, or because the low fluid is a sign of inadequate blood flow to the fetus. Sometimes, a sufficient amount of amniotic fluid can be reestablished with bed rest, medical treatment, and time. Some doctors occasionally use a technique called "amnioinfusion" (directly infusing fluid into the womb with a catheter), particularly to help a fetus tolerate labor, but its advantages are still controversial. If your doctor thinks your baby will have a better chance of growing and developing outside of the womb, she may recommend an elective, preterm delivery.

• Preeclampsia.Preeclampsia is a disease that occurs only during pregnancy. If you have preeclampsia, your blood pressure will be high, you'll have protein in your urine, and your face and hands may swell (different from the annoying, although normal, swollen legs and feet that most pregnant women deal with). Preeclampsia causes blood vessels to tighten, including those going to the placenta, so it can decrease the amount of blood that goes to your fetus. Over time, this can impede his growth and development. If severe, preeclampsia can also cause life-threatening complications for you. It is the most common reason for an elective preterm delivery. Fortunately, preeclampsia always goes away within a few days after delivery.
• Fetal growth restriction.If your baby is growing poorly, it usually means that he isn't getting enough nutrients and oxygen. If the problem is severe, it can cause damage to him, or even stillbirth. Your obstetrician may opt for an elective delivery to prevent these risks, or preterm labor and delivery may occur spontaneously.

Infection

Almost any severe infection in a pregnant woman can be a threat to both mother and fetus, and can lead to a preterm delivery. If you develop an infection, the odds are that you will still carry your pregnancy to term. However, there are some hidden infections that are believed to be responsible for a large number of preterm births. For example, research has linked bacteria that normally live in a woman's genitourinary tract to low-grade infection of the fetal membranes, placenta, and uterus; this infection causes inflammation that, over several weeks or months, can lead to preterm labor or premature rupture of the membranes.

Chronic disease in the mother

If you have a chronic illness, you should discuss with your doctor how it might affect your pregnancy. Many illnesses, if not severe, don't cause substantial problems. But some chronic maternal diseases can disrupt the growth and development of the fetus, or can get worse in the mother during pregnancy because of the bodily changes that occur. Sometimes, a mother needs a medication that she stops taking while she's pregnant because it is dangerous to the developing baby. Her pregnancy may then be electively cut short, so she can safely take her medicine again. Probably the two most common chronic diseases that lead to premature birth are diabetes and high blood pressure.

• Diabetes.If you have diabetes, the amount of sugar in your blood (and therefore, the amount that passes into your fetus) can rise to high levels. Pregnancy makes diabetes worse, because a woman's body is programmed to allow her blood sugar levels to rise higher than usual, so her fetus can get enough fuel. You will be closely monitored with urine and blood tests, and counseled about how you should change your diet, exercise, and insulin injections, if needed. You'll also get ultrasounds, to check on the growth and well- being of your baby. Often, premature delivery in a mother with diabetes is elective, to avoid medical complications in the baby, and a difficult delivery at term. (A baby can grow too big from all that sugar.)

  Gestational diabetes, which comes on during pregnancy, is usually discovered with a simple blood test done at about 28 weeks of gestation. It's more common in women over 30 who are overweight, have high blood pressure, or who have a family history of diabetes. If you find out that you have gestational diabetes, the good news is that you can probably control your blood sugar levels enough, simply by changing your diet, that they won't harm you or your baby. Gestational diabetes usually goes away after delivery, although women who have it are at higher risk of developing diabetes in the future.

• High blood pressure.High blood pressure can be an isolated problem, or it can go along with heart disease, kidney disease, or other medical conditions. High blood pressure can lead to prematurity because it can damage the placenta, or because continuing the pregnancy in the face of a severe underlying disease is harmful to the mother or to the fetus. Women who already have high blood pressure are at greater risk of developing preeclampsia during pregnancy, which often necessitates a premature delivery.

Abnormalities of the fetus

Approximately two to three babies out of a hundred are born with a major birth defect. Premature labor and delivery is common, often because these congenital conditions are associated with other risk factors, such as too much or too little amniotic fluid, poor fetal growth, a chronic maternal disease, or infection. Sometimes, though, the reason for preterm labor and delivery is unknown. If you find out that your baby has a serious abnormality, you and your doctor will make plans in advance for the best possible treatment for both you and your baby before, during, and after delivery.

Social and behavioral factors

Overall, women of lower socioeconomic status with less education are more likely to have premature babies. Because many social and behavioral risk factors go together, it's hard to evaluate their individual roles. Here are some of them:

• Little or no prenatal care.Women who are rarely seen by an obstetrician or midwife during pregnancy are more likely to deliver prematurely. However, attempts to make prenatal care more available have not been successful in reducing rates of prematurity.
• Ethnicity.African-American women have a higher rate of preterm birth than Hispanic and Caucasian women of the same socioeconomic level, for unknown reasons.
• Smoking.Cigarette smoking reduces blood flow to the placenta, and oxygen to the fetus. It is clearly connected to poor fetal growth, preterm rupture of membranes, and premature birth. Cigarette smoke and nicotine also increase the chance of placental abruption and placenta previa. The risk for your baby increases with the number of cigarettes you smoke. Ideally, you should quit smoking before you conceive, but it's never too late: even cutting back on cigarettes in the second half of your pregnancy can reduce your risk of having a small for gestational age or premature baby.
• Drug abuse.Some street drugs, such as cocaine, marijuana, and amphetamines, are associated with preterm birth. Cocaine can cause placental abruption.
• Sexual activity.Studies have not found a clear link between sexual activity, orgasm, and prematurity. Still, most obstetricians will advise you to avoid sexual intercourse if you've had episodes of premature labor, rupture of membranes, or bleeding. That's because sex can cause some minor injury to your cervix, or spread infection into your uterus, and the resulting inflammation could cause a preterm birth.
• Physical exertion.Heavy labor or long work hours may be associated with preterm labor and delivery, although proof for that is indirect. There is no evidence that women who exercise moderately during pregnancy increase their odds of having a premature baby.
• Low maternal weight.Women who weigh less than 100 pounds at the start of pregnancy, or who gain too little weight during pregnancy, have an increased chance of delivering prematurely. Maternal malnutrition can also impair the fetus's growth. Your obstetrician will check on your weight gain throughout pregnancy, and if it isn't sufficient, will counsel you to eat more or better. Never take the initiative of adding vitamins, minerals, or supplements to your diet without your doctor's permission, though, because some supplements, especially in large quantities, can harm your baby. It's true what your mother told you: the best source of nutrients is a varied, balanced diet.
• Age younger than 18 or older than 40 years.If you're in one of these age groups, but don't have other risk factors for prematurity, your chance of having a premature baby is increased, but just by a small amount.

Copyright © 2000 by Dana Wechsler Linden, Emma Trenti Paroli, and Mia Wechsler Doron, M.D.

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Excerpted from Preemies - Second Edition: The Essential Guide for Parents of Premature Babies by Dana Wechsler Linden, Mia Wechsler Doron, Emma Trenti Paroli
All rights reserved by the original copyright owners. Excerpts are provided for display purposes only and may not be reproduced, reprinted or distributed without the written permission of the publisher.