Hormonal regulation of pregnancy

Welcome to this lecture on hormonal regulation of pregnancy, providing an overview of the key hormonal changes throughout pregnancy, including the roles of HCG, progesterone, estrogen, and placental hormones in supporting both the fetus and maternal adaptations. We will examine how the placenta assumes hormonal control, the mechanisms that trigger labor, and the dramatic shifts that occur with delivery and postpartum recovery. The lecture will also address how disruptions in these processes can impact pregnancy outcomes and highlight the evolutionary dynamics shaping maternal fetal hormone interactions. Pregnancy is a remarkable state that relies on a finely tuned hormonal orchestra. Hormones sustain the developing fetus and adapt nearly every maternal system. Core hormones, human chorionic gonadotropin, HCG, progesterone and estrogen, play distinct roles at various stages. The placenta's emergence as an endocrine organ dramatically alters the maternal environment. This lecture explores how these hormonal shifts support pregnancy, drive maternal changes, and prepare mother and fetus for labor and beyond. The earliest signals of pregnancy come from HCG, produced by the embryos trophoblast soon after implantation. Detected in maternal blood, HCG is the target of home pregnancy tests. Its main function is to rescue the corpus luteum, which secretes progesterone and estrogen to prevent menstruation and support the uterine lining. As the placenta matures, it takes over hormone production in a critical shift