1Maternal adaptations to pregnancy and the role of the placenta

Delivery of an optimally grown, viable infant defines a successful pregnancy. Optimal growth is achieved by the interaction of maternal, placental, and fetal systems to deliver maternal nutrients to the placenta, transfer them to the fetus, and maximize their utilization for fetal growth. Pregnancy is characterized by profound changes in thematernal immune,metabolic, cardiovascular, and renal systems to ensure a successful pregnancy and adequate fetal growth. The fetalplacental unit secretes many hormonal signals, the roles of which include redirecting maternal physiology and metabolism to direct substrate toward the fetus and support normal fetal growth. The physiological adaptations of pregnancy begin shortly after conception, indeed before the establishment of a fetalplacental unit, and thus in their early phases must be directed by maternal signals, including those from the corpus luteum. Subsequently feto-placental signals play a major role in regulation of maternal metabolism.This chapter describes thematernal adaptation to pregnancy and the role of the placenta in nutrient transfer to the fetus.