This book presents recent knowledge, research, and theory about the earliest developmental period—from conception to birth—which holds even greater consequences for the health and development of the human organism than was previously understood. Theory and research in multiple disciplines provide the foundation for the exploration of how experiences during conception and time in the womb; during and after birth; and experiences with caregivers and the family system in the early postnatal period impact an individual physically, cognitively, emotionally, and socially over their life span.Knowledge drawn from numerous fields highlights the opportunity for parents-to-be and the practitioners who care for them to intentionally support the cultivation of nurturing internal and external environments during the preconception, prenatal, and early parenting periods. Theory and research from the fields of psychology, medicine, psychophysiology, epigenetics, and traumatology, among others, suggest that doing so will support lifelong multidimensional aspects of healthy development in children and adults and may also benefit future generations.