How do estrogen and progesterone help regulate the female reproductive cycle?

Estrogen and progesterone are the primary ovarian hormones that regulate the female reproductive cycle through a complex interplay with the pituitary gland and the hypothalamus.123

The Follicular Phase

During the first half of the cycle, follicle-stimulating hormone (FSH) promotes the maturation of ovarian follicles, which secrete increasing amounts of estrogen. Rising estrogen levels stimulate the proliferation of the uterine lining and eventually trigger a surge in luteinizing hormone (LH), which induces ovulation.123

The Luteal Phase

Following ovulation, the ruptured follicle transforms into the corpus luteum, which produces large quantities of progesterone. Progesterone prepares the endometrium for potential implantation of a fertilized egg and inhibits uterine contractions.1243

Feedback and Cycle Conclusion

The interaction between these hormones provides critical feedback to the brain:
* Inhibition: High levels of progesterone and estrogen suppress further ovulation to ensure undisturbed development if pregnancy occurs.34
* Menstruation: If fertilization does not occur, the corpus luteum degenerates, causing a sharp drop in hormone levels. This withdrawal triggers the shedding of the uterine lining, known as menstruation, and allows a new cycle to begin.124