The menopause and hormone replacement therapy

Abstract Natural menopause is the permanent cessation of menstruation resulting from the loss of ovarian follicular activity. It is confirmed after 12 consecutive months of amenorrhoea for which there is no other obvious cause. The average age at natural menopause, about 51 years, has been constant for centuries. A majority of women experience natural menopause between ages 45 and 55 years. Cigarette smoking, a vegetarian diet, and simple hysterectomy are each associated with an earlier (by 1–2 years) average age at menopause. Premature menopause (last menstrual period before age 40) can follow bilateral oophorectomy, chemotherapy, or radiation (i.e. induced menopause), or be caused by premature ovarian failure.