Early or premature menopause is defined as menopause before the age of 40. Premature ovarian failure, surgery, and chemotherapy may all result in early menopause. About one in a hundred women may experience early menopause; some may be teenagers or in their twenties. Symptoms of early menopause tend to be very similar to those of normal menopause. Changes in the timing and duration of menstrual periods and hot flashes are common.

In some women, early menopause may be due to failure of the ovaries and is called premature ovarian failure. It is thought that such failure is due to hormonal, autoimmune or genetic processes, which result in a depletion in the number of viable eggs in a woman