Menopause, which normally occurs between the ages of 40 and 55, is a natural event in a woman's life. On average, menopause begins at about age 51. During menopause ovulation (egg production) ceases, eliminating the possibility of pregnancy, and menstruation becomes less frequent and eventually stops. In some women, menstrual activity stops suddenly, but usually it tapers off, both in amount and duration of flow, and frequently the menstrual periods become more closely or more widely spaced. This irregularity may last for 2 or 3 years before menstruation finally ceases.

The symptoms of menopause are caused by changes in estrogen and progesterone levels. As the ovaries become less functional, they produce less estrogen/progesterone and the body subsequently reacts. Some women experience few if any symptoms, while others experience various symptoms ranging from mild to fairly severe. This variation is normal. A gradual decrease of estrogen allows the body to slowly adjust to the hormone change, but in some women a sudden decrease in estrogen level occurs, causing severe symptoms. This result is often seen when menopause is caused by surgical removal of the ovaries (surgical menopause).

Estrogen is responsible for the buildup of the epithelial lining of the uterine cavity. During the reproductive years this lining builds and is then shed (menstruation) on a monthly basis (usually). The menopausal decrease in estrogen prevents this buildup from occurring. However, androgenic hormones produced by the adrenal glands are converted to estrogen, and sometimes this will cause postmenopausal bleeding. This is usually nothing to worry about, but because postmenopausal bleeding may be an early indication of other problems, including cancer, it should always be checked by a physician.

A reduction in estrogen is associated with a number of side effects that can be very annoying. Hot flashes, caused by an increase of blood flow in the blood vessels of the face, neck, chest and back, and vaginal dryness, caused by thinning of the tissues of the vaginal wall, are the two side effects most frequently experienced. The mood changes and lack of sex drive that are also sometimes associated with menopause may result partially from the hormone decrease, but may also result from having to deal with hot flashes and vaginal dryness. In addition to these side effects there are others that may go undetected for many months or years. Decreased estrogen levels increase the risk for osteoporosis (loss of calcium from the bones, causing bone fragility), which sometimes isn't detected until a bone fracture occurs.