Follicle-stimulating hormone (FSH) is a hormone produced by the pituitary gland in the brain. It plays a crucial role in regulating the reproductive processes in both men and women. In women, FSH stimulates the growth of ovarian follicles, which contain eggs, and is essential for the menstrual cycle. In men, FSH is important for the production of sperm. FSH levels fluctuate throughout the menstrual cycle and can be measured through blood tests. Abnormal levels of FSH can indicate various health issues, such as infertility or pituitary disorders. Monitoring FSH is important for understanding reproductive health.