Which hormone is crucial for maintaining the uterine lining during early pregnancy?

Progesterone is the hormone that plays a vital role in maintaining the uterine lining during early pregnancy. After fertilization occurs, the developing embryo begins to produce human chorionic gonadotropin (hCG), which signals the corpus luteum in the ovary to continue producing progesterone. This hormone is responsible for thickening and stabilizing the endometrium (the uterine lining), creating a supportive environment for the implanted embryo. Without adequate levels of progesterone, the uterus would not be able to sustain the embryo, and the pregnancy would be at risk for miscarriage.

While estrogen also plays an important role in pregnancy by supporting the development of the uterine lining and other functions, it is progesterone that is specifically essential for maintaining the lining during the critical early stages after implantation. Oxytocin is more involved in initiating labor and breastfeeding, and prolactin primarily functions in milk production and breastfeeding, making them less relevant to the maintenance of the uterine lining during early pregnancy. Thus, the crucial nature of progesterone in sustaining the early stages of pregnancy is clear.