Estrogen

Menopause, defined as the permanent cessation of menstruation, is the final stage in the process of female reproductive aging. Because of the dramatic increase in life span during the twentieth century, the average woman in this country experiencing menopause has more than one-third of her life ahead of her, and as of the late 1990s, an estimated thirty-five million American women were postmenopausal. In practical terms, menopause can only be diagnosed "after the fact," that is, after a period of twelve months of amenorrhea (absence of menstruation). The average age of menopause is fifty-one, which is preceded by a two- to eight-year period of changing ovarian function, known as perimenopause.

In addition to the variability in the age of menopause and in the length of perimenopause, there is also great variability in the extent of menopausal symptoms. The types of symptoms reported include hot flashes (sensation of warmth, frequently accompanied by skin flushing and perspiration), insomnia, night sweats, depression, headache, backache, painful intercourse, loss of sex drive, vaginal dryness, and problems with short-term memory. Cultural differences may play a role in some of the reporting of symptoms, and it is also possible that different concepts of what is discomfort, or real lifestyle differences, such as exercise and diet, may actually diminish these phenomena in some cultures.