What hormone is primarily responsible for triggering ovulation?

Luteinizing hormone (LH) is the primary hormone responsible for triggering ovulation in the menstrual cycle. This process occurs through a surge in LH levels, which stimulates the mature ovarian follicle to release an egg from the ovary. This event typically takes place around the midpoint of the menstrual cycle and is crucial for fertility.

During a woman's cycle, follicle-stimulating hormone (FSH) plays a key role in the initial development of the ovarian follicles, but it is the LH surge that specifically prompts ovulation. Estrogen levels rise as the follicles mature, contributing to the regulation of the cycle and the LH surge itself, but it does not directly trigger ovulation. Progesterone, on the other hand, is involved in maintaining the uterine lining after ovulation and preparing the body for potential pregnancy, but it does not trigger the release of the egg.

Understanding the interplay of these hormones helps clarify why LH is specifically designated as the hormone that triggers ovulation.