Hormones are chemicals that control when and how certain organs work. They are made by glands in the body. In women, the hormone estrogen (made primarily by the ovaries), plays a key role in the reproductive system, menstrual periods, menopause, and the health of bones, heart, and blood vessels.

Estrogen is made during the entire menstrual cycle, causing the lining of the uterus (endometrium) to thicken each month. The amount of estrogen produced by the ovaries slowly decreases as women age, causing the menstrual period to stop. A sudden drop in estrogen can also occur if the ovaries are removed surgically.

Menopause is defined as no period for one year. During the time before an after menopause, a woman produces less estrogen, possibly resulting in hot flashes, mood swings, and vaginal dryness, as well as possible bone loss (osteoporosis). Because of this, many women take HRT to restore estrogen and progesterone after menopause.

Women who have a uterus may need to take both estrogen and progesterone, and those who have had their uterus removed may need just estrogen.

HRT can be given by pills, patches, creams or gels. Your doctor may prescribe one of these types of therapy. HRT may be the best way to treat some health problems that confront women at menopause. Although there may be a small risk associated with HRT, it also offers long-term benefits that can improve womens health and quality of life.