Overview

During her reproductive years, a woman's ovaries produce the hormones estrogen and progesterone in the ovaries. Estrogen works to regulate a woman's monthly menstrual cycle and secondary sexual characteristics (such as breast development and function), and also rises at different times in the menstrual cycle to prepare the body for fertilization and reproduction. Progesterone also rises in a cyclical fashion to prepare the uterus for possible pregnancy and to prepare the breasts for lactation (milk production). As a woman reaches menopause, typically around 50 years old, her body produces less and less estrogen and progesterone. It is estimated that 40 million women will reach menopause in the next 20 years.

Decreased levels of estrogen during menopause may cause hot flashes, vaginal dryness, sleep disturbances, or other bothersome side effects. The dryness of tissue surrounding the vagina and urethra may cause pain during sexual intercourse or urination, and HRT helps to relieve these and other menopausal symptoms. Hormone replacement therapy (HRT) is synthetic estrogen and progesterone (progestin) designed to "replace" a woman's depleting hormone levels.

Past research has shown that HRT may also help prevent osteoporosis, heart disease, short-term memory loss, depression and other diseases in post-menopausal women. However, recent research has found that HRT may not provide these benefits and may pose other risks, including an increased risk of ovarian cancer (with long-term use) and cancer of the uterine lining (in women do not take progestin with estrogen). See sections below for more information. While HRT is highly effective at relieving menopausal symptoms and may provide protection against conditions such as osteoporosis, there is also some evidence that supports a link between HRT and an increased risk for breast cancer. In July 2002, the National Institutes of Health halted a large study on HRT, called the Women's Health Initiative because the combined estrogen/progestin regimen of the therapy was found to cause 8 cases of invasive breast cancer for every 10,000 women on HRT (a 26 percent increase in breast cancer risk compared to women who do not take HRT) (1). Though these numbers can be alarming, some experts believe that limited, short-term use of HRT can be safe among some women who are not at high risk of breast cancer or other diseases. Therefore, patients and physicians should make the decision about HRT together, based on the individual medical situation. See the HRT and breast cancer section below for more information.

Menopause

Menopause is the time in a woman’s life when she stops menstruating, signaling the end of her reproductive life. Natural menopause typically occurs in women when they are in their late forties or early fifties. However, some women will go through menopause at an earlier or later age. Menopause is considered premature if it occurs before age 35. Premature menopause may occur for several reasons, including certain types of cancer treatment, mumps and certain autoimmune disorders such as lupus or rheumatoid arthritis. Also, women who smoke tend to go through menopause at an earlier-than-average age.

Before menstruation stops at menopause, a woman will go through premenopause and perimenopause. During premenopause, menstrual periods begin to become irregular. During perimenopause, a woman’s menstrual periods will become highly irregular and she may experience symptoms of menopause, such as hot flashes, vaginal dryness, or sleep disturbances. Perimenopausal occurs a few years before a woman reaches menopause. Once a woman reaches menopause, menstruation will stop forever unless she takes HRT.

Symptoms and Effects of Menopause

The symptoms of menopause vary significantly from woman to woman. Some women only experience mild menopausal symptoms while others have severe discomfort. The most common symptom of menopause is hot flashes. Hot flashes may be accompanied by sweating, flushing, or heart palpitations. It is estimated that more than 60% of menopausal women experience hot flashes.

During menopause, changes also occur in the vagina and urinary tract. Vaginal tissue becomes thinner, drier, and less elastic, which may cause discomfort or pain during sexual intercourse. Urinary tract tissue also becomes less elastic, which may cause a release of urine during laughter, coughing, sneezing, or exercise. Many menopausal women also find that urinary tract infections occur more frequently during this time. Other symptoms of menopause may include mood changes, insomnia (or other sleep disturbances), depression, or anxiety. HRT can relieve many of these symptoms.