Nutrition and Stress and the Developing Fetus

The most dramatic events in the growth and development of an infant occur before birth and result from the dynamic interplay of the fetus’s genetic potential and appropriate environmental stimuli, a process termed epigenetics (Kelly & Trasler, 2004). While this process may be viewed as a progressive unfolding and continuum, it now recognized that fetal life is characterized by “critical” or “sensitive” periods wherein exposure to specific environmental stimuli is required for the normal sequence of development of both anatomical structures and their subsequent functioning. Thus, the previously held concept that the fetus is safe from the vagaries of the maternal state and is functionally the equivalent of an obligatory parasite is no longer tenable. In particular, it is clear that the nutritional state of the mother, both quantitatively and qualitatively, has a major effect on fetal growth and development. This is best exemplified by the now understood role of folic acid in the development of the neural tube. Mothers who delivered infants with defects such as anencephaly and spina bifida were noted to have lower serum levels of folic acid. Conversely, women who took supplementary folic acid at the time of conception through the first trimester were substantially less likely, as compared to women who did not take folic acid, to deliver a fetus with neural tube defects. The protective advantage of supplementary folic acid was even more dramatic in those mothers who had already delivered an infant with a neural tube defect. Such results clearly confirm the critical importance of timing and the interplay with genetic predisposition when discussing nutritional factors as related to development (American Academy of Pediatrics Committee on Genetics, 1999; Czeizel & Dudas, 1992).