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What does follicle-stimulating hormone do during the menstrual cycle?

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Diagram of the menstrual cycle showing hormone levels, follicle development, and endometrial changes across 28 days. It highlights menstruation, ovulation, and the follicular and luteal phases, with labeled curves for estrogen, progesterone, FSH, and LH. — menstruation Cyclical changes during a woman's normal ovulatory menstrual cycle.

Follicle-stimulating hormone (FSH) is a gonadotropic hormone secreted by the pituitary gland that plays a critical role in the menstrual cycle.123

During the follicular phase, FSH is essential for the development and maturation of ovarian follicles, which are the structures that contain immature eggs. Specifically, FSH promotes the growth of these follicles and stimulates the synthesis of estrogens within the cells lining the follicles.123

This rhythmic, cyclical secretion of FSH is necessary for monthly ovulation. As the cycle progresses, there is a preovulatory surge in FSH and luteinizing hormone (LH) concentrations, which facilitates the final stages of follicular maturation. The activity of FSH is regulated in part by inhibin, a hormone secreted by the developing follicles that inhibits further FSH release from the pituitary.13