The ovaries are small, oval-shaped glands that are located on both sides of the uterus. Ovaries produce the sex hormones progesterone and estrogen. These hormones promote the healthy development of female sex characteristics during puberty and they help ensure a woman’s fertility. The ovaries also release the hormone relaxin prior to when a woman gives birth, as well as inhibin, which signals the pituitary to throttle down the production of follicle-stimulating hormone. The ovaries are about four centimeters long and are held in place by ligaments that are attached to the uterus. Unlike testicles in the adult male which are constantly producing sperm, females are born with approximately one to two million eggs that will last them throughout their entire lives. By the time a girl reaches puberty, this number of egg decreases to about 400,000. Approximately 300 to 400 eggs will be released during a woman’s lifetime through the process of ovulation. Usually, only a single egg from one ovary is released midway during each menstrual cycle.