It is not a disease. Menopause is a normal, natural event—defined as the final menstrual period and usually confirmed when a woman has missed her periods for 12 consecutive months (in the absence of other obvious causes). Menopause is associated with reduced functioning of the ovaries due to aging, resulting in lower levels of estrogen and other hormones. It marks the permanent end of fertility. Menopause occurs, on average, at age 51. It occurs most often between ages 45 and 55. The term “premenopausal” refers to the phase of life that precedes menopause. For many women, it is an optimal time to reassess their health.