Remarkable diversity of size and health of offspring exists after normal pregnancies. When pregnancies are complicated by an extrinsic variable such as inappropriate maternal nutrition, birth weight and health of the neonate are substantially affected. The placenta is the organ through which respiratory gases, nutrients, and wastes are exchanged between the maternal and fetal systems. Thus, transplacental exchange provides for all the metabolic demands of fetal growth. Transplacental exchange is dependent upon uterine and umbilical blood flow, and blood flow rates are in turn dependent in large part upon vascularization of the placenta. Therefore, factors that influence placental vascular development will have a dramatic impact on fetal growth and development, and thereby on neonatal mortality and morbidity. Recent work from our laboratories has focused on the effects of nutrient intake during pregnancy on placental growth and vascular development. Both nutrient restriction of the adult dam and overnourishment of the adolescent dam during pregnancy suppress placental cell proliferation and vascularity. Furthermore, placental expression of angiogenic factors and their receptors, factors that are known to affect vascular growth, are perturbed by level of nutrition. Studies in this area will lead to improved methods to manage nutritionally-compromised pregnancies.