Menopause is the permanent cessation of menses following the loss of ovarian follicular activity. The median age at the onset of menopause in the United States is 51 years. In retrospect, the average life expectancy for women is 79.7 years. Thus, American women can expect to be postmenopausal for more than one-third of their lives.

Menopause is important because the decline of sex steroids in approximately two-thirds of women results in symptoms that adversely affect quality of life and increase the risk for osteoporosis and possibly coronary heart disease. Menopausal symptoms may include hot flashes, night sweats, vaginal dryness, mood swings, depression, insomnia, myalgia, and urinary frequency.