Steroid hormones [Esteroides en el embarazo]

Human placenta has a key role in the events cascade leading to the fetal-maternal adaptations to pregnancy, as well as to the onset of term and preterm labor. The final pathway of this cascade is represented by the secretion of steroid hormones, as placenta, decidua, pregnant myometrium, and the embryo/fetus serve as targets to steroid hormones. Indeed, steroid hormones represent the common final pathway of a complex placental network of interactions acting from implantation till delivery. Indeed, progesterone prepares the endometrium for implantation, inhibits uterine contractility, and prepares mammary glands for lactation; allopregnanolone is involved in the mood and adaptation to stress; estrogens affect uterine myometrial growth and enlargement, relaxation of pelvic ligaments, and myometrial contractility; cortisol is involved in the mechanism regulating fetal growth and adaptation to the extrauterine lige (i.e. fetal lung maturation), glucose metabolism and myometrial contractility. Steroid hormones in pregnancy may play a role in the regulation of maternal and fetal physiology during pregnancy, ranging from the control of placental anchoring to fetal growth, maturation and/or initiation of labor.