Endocrine Changes in Pregnancy

The placenta supports the metabolic needs of the developing fetus and has numerous and intertwined endocrine functions that affect both mother and fetus in sex-specific ways. Peptide and steroid hormones produced in the placenta result in significant physiologic changes in the pregnant woman in nearly all organ systems, including the endocrine system. Lactotroph numbers and prolactin production increase in the pituitary, thyroid gland size and thyroid hormone requirements increase, insulin resistance increases, and the activity of the renin-angiotensin system in the kidney increases. Whereas many endocrine changes during pregnancy result from altered hormone levels produced outside of pregnancy, some hormones are unique to the placenta, such as human chorionic gonadotropin and human placental lactogen. Several of these unique compounds can be used for genetic screens to assess fetal risk of aneuploidy and other genetic abnormalities. A complex set of endocrine signals helps sustain a pregnancy, and an equally intricate series of hormonal changes triggers labor and ultimately results in the end of the pregnancy with delivery of the infant. Interactions between mother and fetus continue after delivery, particularly but not exclusively surrounding lactation and feeding.