Maternal nutrition before and during pregnancy.

In humans, the link between the maternal diet and the outcome of pregnancy is best illustrated by the classic study of wartime famine in Holland. During the famine it is likely that a low food intake reduced the glucose stream from the mother to fetus and gave rise to smaller size at birth. Maternal glucose production is also influenced by the type of carbohydrate in the diet. Even when famine and starvation are not issues, a low dietary glycemic index can alter maternal blood glucose production and the area under the glucose curve, and give rise to reductions in fetal growth and infant weight at birth. Reduced food intake in famine areas would also reduce the concentration of micronutrients in the maternal diet. Two micronutrients (iron and folate) have effects on pregnancy outcome that have been shown with some consistency in pregnant women. Emerging evidence now suggests that use of micronutrient- containing prenatal vitamins before and during pregnancy is associated with reductions in the risk of congenital defects, preterm delivery, low infant birthweight, and preeclampsia.