Menopause is the final menstrual period that a woman experiences in her lifetime. Since periods often become very irregular towards the end of a woman’s reproductive years, menopause is not diagnosed until a woman has not had her period for 12 consecutive months in the absence of other causes. The ovaries stop producing large amounts of estrogen (and progesterone) and women no longer ovulate. Many other changes take place in the body when this happens. In the United States, the average age of women when they enter menopause is 51.