Ovulation is part of the normal menstrual cycle. It is stimulated by several different hormones during the first half of the 28-day cycle. An increase in follicle-stimulating hormone makes several follicles, each containing an egg, develop in the ovary. Later in the cycle, the follicle-stimulating hormone level drops. The female hormone estrogen then stimulates one egg to mature inside a follicle. Luteinizing hormone then stimulates the follicle to release the egg, causing ovulation.
