Which hormone plays a crucial role in regulating the menstrual cycle?

Progesterone plays a crucial role in regulating the menstrual cycle as it specifically prepares the endometrium (the lining of the uterus) for potential implantation of a fertilized egg after ovulation. Following ovulation, the corpus luteum, which is formed from the ovarian follicle, secretes progesterone. This hormone helps to maintain the uterine lining and also suppresses further ovulation within that cycle.

In the absence of fertilization, progesterone levels decline, leading to the shedding of the endometrial lining, which is recognized as menstruation. The cyclical rise and fall of progesterone, along with estrogen, are essential for orchestrating the various phases of the menstrual cycle, including the follicular phase, ovulation, and luteal phase.

Other hormones mentioned, like insulin, cortisol, and thyroid hormone, while important for overall health and metabolic functions, do not directly regulate the menstrual cycle. Insulin is involved in glucose metabolism, cortisol is a stress hormone that can affect various bodily functions but is not directly tied to reproductive processes, and thyroid hormones regulate metabolism but do not play a direct role in menstrual cycle regulation.