MENOPAUSE

the period of time during a woman's life marked by cessation of menstruation and termination of the potential for reproduction. The average age of onset is about 48 years, but menopause may begin as early as age 40 or as late as the early 50s. Artificial menopause can be induced by surgically removing or by irradiating the ovaries. The human ovaries function actively for about 35 years. Menopause is the result of a progressive decline in ovarian function due to aging. During a woman's reproductive years, the follicles of the ovaries, under the stimulation of hormones released by the pituitary gland, periodically rupture and discharge their ova (eggs). As menopause approaches, some follicles fail to rupture, and their ova are not discharged; later all the follicles fail to rupture. The cycle of menstruation is disturbed by this failure to ovulate. The continuing decline in ovarian activity may result in missed periods, longer intervals between periods, irregular bleeding, varying lengths of periods, or a decrease or increase in menstrual flow. In a minority of women, the menstrual periods cease abruptly. During menopause the ovaries produce progressively smaller amounts of the hormone estrogen. This decrease affects the hormonal activity of other glands that regulate the reproductive function and disturbs the neurovascular mechanism of the hypothalamic region of the brain. These disturbances probably give rise to the brief flushes, or hot flashes, that are a characteristic symptom of menopause. A woman may begin experiencing hot flashes before the obvious onset of menopause and may continue to have them for a few months or for two or three years. The hot flash, often experienced as a sense of warmth, flushing of the face and body, a prickling sensation, and sweating, may occur several times a day. Other symptoms of menopause such as nervousness, headaches, or dizziness may have a psychological origin stemming from a fear of aging or from changing patterns of life and family relationships. Weight gain may result from increased food intake and decreased physical activity. The medical management of menopause entails education to reduce fear or anxiety, periodic physical examination, and in some cases the administration of estrogenic hormones. final cessation of menstruation and therefore the end of a woman's reproductive life. The popular term change of life is neither descriptive nor accurate, for it tends to indicate a physical, mental, and sexual deterioration, whereas deterioration does not occur. In most women, menopause begins between the ages of 45 and 55 years. Although the average age for onset is about 50 years, menopause may begin as early as age 40 or be delayed to the late 50s. Although the age of onset is probably determined by the hereditary background of the individual, good nutrition and health habits tend to postpone onset. A premature menopausei.e., one that takes place spontaneously before the age of 40occurs in about 8 percent of women. An artificial menopause may be induced by removing the ovaries by surgery or by destroying them with X rays or radium. The natural life of the ovaries is about 35 years. The menopause is brought on by a progressive decline in ovarian function. This decline is a normal result of aging and is accelerated as the menopause approaches. During the reproductive years follicles in the ovaries mature and release their ova periodically under hypothalamic-pituitary stimulation. In the years immediately preceding the menopause, however, first some follicles and later all follicles fail to rupture and release their ova. The failure to ovulate results in a disturbed menstrual pattern. A woman may miss a period or two and suspect pregnancy. A medical examination, however, will establish the proper diagnosis. The continued decline in ovarian activity may provoke prolonged intervals between periods or irregular bleeding episodes. The length of the periods may vary, and the flow may become either more scant or profuse. In a fortunate small minority the periods cease abruptly. As the ovaries decline in function, they produce smaller and smaller amounts of the hormone estrogen; this decline in estrogen initiates subtle rearrangements in the hormonal activity of the glands that control the reproductive function. The decrease in output of estrogen disturbs the neurovascular mechanism of the hypothalamus and probably initiates the vasomotor changes that may provoke the characteristic hot flashes of the menopause. The metabolism of the pituitary gland is altered and increasing amounts of follicle stimulating hormone (FSH) appear in the blood and urine. Rearrangements in the hormonal activity of the adrenal and thyroid glands also take place, for the metabolic activities of all these glands are interrelated. These adjustments are usually made without physical or mental disturbances in most women. Hot flashes are the only characteristic symptoms of the menopause. They often appear before its obvious onset and their duration is usually limited to two or three years. The young woman who has her ovaries removed for disease or other reasons will develop flashes within a week following the operation. The hot flash usually begins as a sense of warmth over the upper chest. It then spreads to the neck and face and may extend over the entire body, sometimes giving rise to a prickling sensation. The woman is acutely aware of blushing, which usually is disturbing to her, particularly in company. The flashes may recur frequently during the night and may interfere with sleep. She may awaken because of a chilly sensation and may perspire freely. A variety of other symptoms can and do occur, although many are entirely unrelated to the changes incidental to the menopause. Nervousness, headaches, and dizziness are common complaints. The fear of aging, the altered pattern of life, and changing family relationships also may precipitate many disturbing symptoms. Many women complain of weight gain during the menopause. Occasionally this is related to decreased thyroid function. In most cases, however, it is brought about by decreased physical activity and by increased food intake. The menopause is not necessarily associated with unusual changes in physical appearance and fitness. The administration of estrogenic hormonesonce a widely approved remedy for relief of menopausal symptoms and also believed to retard the development of atherosclerosis and osteoporosis (bone decalcification)has been associated with increased incidence of endometrial cancer and is being reevaluated. M. Edward Davis The Editors of the Encyclopdia Britannica Additional reading Information on menopause may be found in Linda R. Gannon, Menstrual Disorders and Menopause: Biological, Psychological, and Cultural Research (1985); and Herbert J. Buchsbaum (ed.), The Menopause (1983). The Editors of the Encyclopdia Britannica