Overview of Menopause
Menopause is a normal biological event that occurs when a woman's ovaries stop producing female hormones (e.g., estrogen and progesterone) and menstrual cycles end. Menopause is not a disease and it can be a positive emotional and physical transition.
Technically, menopause occurs with the final menstrual period and involves only 1 day. The hot flashes, mood swings, and other symptoms associated with menopause occur during perimenopause, the transitional years preceding and following actual menopause. The word "menopause" is used throughout this document to refer to menopause and perimenopause.
By the time a woman stops menstruating, many of the symptoms associated with menopause have persisted for several years. Postmenopausal women are at greater risk for heart disease and osteoporosis.
It usually takes 6 to 12 months or longer of no menstrual bleeding (amenorrhea) before a woman can be certain that she has experienced menopause. Menopause usually occurs naturally, but can be induced by certain types of surgery (e.g., hysterectomy; called surgical menopause), chemotherapy, and pelvic radiation therapy.
Researchers estimate that more than 1.3 million women in the United States and 25 million women worldwide experienced menopause in the year 2000. There are about 470 million postmenopausal women worldwide, a number that is expected to increase to 1.2 billion by 2030.
Symptoms associated with menopause can be reduced by diet and lifestyle changes. Hot flashes are the most common symptom associated with menopause. Menopausal women should make sure to get adequate calcium in their diet and daily exercise. There are several self-care guidelines involving diet and lifestyle. In some cases, hormone replacement therapy (HRT) and Raloxifene are used to treat symptoms of menopause.
Menopause usually occurs from mid-40s to the late 50s. The average age of natural menopause is 51. Menopause that begins before the age of 40 is considered premature and is usually associated with surgery or other medical intervention.
Early menopause (i.e., not necessarily premature) is associated with the following factors:
- Nulliparity (i.e., women who have never been pregnant)
- Medically treated depression
- Exposure to toxic chemicals
- Treatment of childhood cancer with pelvic radiation or alkylating agents
Late menopause is associated with these factors:
- More than one pregnancy (multiparity)
- Higher than normal weight-to-height ratio (Body Mass Index, or BMI)
- Higher cognitive scores in childhood
Menopause & Hormonal Changes
Menopause is characterized by important hormonal changes. In particular, the ovaries stop producing estrogen and progesterone. In most women, hormone production slows many years before menopause.
Estrogen and progesterone play essential roles in the menstrual cycle, stimulating changes in the uterine lining and the onset of menstrual bleeding. Even though their primary role is reproductive, these hormones affect other tissues in the body as well, including the breasts, bones, blood vessels, GI tract, urinary tract, heart, and skin. When the ovaries stop producing estrogen and progesterone, menstruation ceases and women experience other changes as well.
The production of estrogen and progesterone does not stop completely at menopause. The ovaries and adrenal glands (located on top of the kidneys) continue to produce androstenedione, a hormone that is converted into estrogen. The decline in estrogen is substantial enough to cause symptoms that may be alleviated with hormone replacement therapy.