Natural menopause refers to the normal end of reproductive fertility that occurs when women stop ovulating and no longer have menstrual cycles. Menopause usually occurs in women between the ages of 45 and 55, with the average age in the U.S. being 51. Leading up to menopause, your periods may become irregular and taper off over several years or they may cease abruptly. Some women experience early menopause because of surgery (removal of the ovaries or uterus), illness, or other reasons. Some women experience debilitating side effects during the transition to menopause but there are treatment options available in the form of hormone therapy.