Fetal programming: Prenatal origins of health and illness

ABSTRACT—Research on young animals and humans has demonstrated the critical importance of the fetal stage as a formative period in normal development. However, the significance of these findings has not always been incor-porated into our thinking when trying to elucidate the or-igins of health and disease. It is not only that babies react to the state of the mother and to salient environmental events while still in the uterus.This stimulationandpriming seems to be essential for guiding the optimal maturation of the nervous, endocrine, and immune systems. Experiences during prenatal life also program the regulatory set points that will govern physiology in adulthood. During this malleable maturational phase, these biological processes should be viewed as flexible ‘‘learning systems’ ’ that guide the developmental trajectory toward health or derail i