Menopause is the time in a woman's life when her normal menstrual periods have stopped for at least 12 months and she can no longer become pregnant. It is a natural part of female aging. Menopause can occur anytime after the age of 35, but the typical age of onset is in the late 40s to early 50s; the average age of onset in American women is 51.
During child-bearing years, the hormones FSH (follicle-stimulating hormone), LH (luteinizing hormone), estradiol, and progesterone work in concert each month to develop and release an egg from the ovaries (ovulate) and to either regulate the monthly menstrual period or support the beginning of a pregnancy. As menopause approaches, the cyclical production of estradiol and progesterone by the ovaries diminishes and becomes less consistent.
The beginning of the menopausal process is called menopausal transition or perimenopause. It may begin sometime in a woman's 40s, but may be earlier in the late thirties. It is a gradual process and usually takes two to five years to complete.
During perimenopause, hormone levels can fluctuate high to low from one month to the next, with periods and ovulation becoming irregular. A woman may have a period and then go for several months before having another, and some women may find that the frequency and intensity of their periods actually increase during perimenopause. Even though irregularities during menopause transition are to be expected, a woman should discuss all changes with her healthcare practitioner so that she can ensure that symptoms are not being caused by something other than hormone fluctuations. Perimenopausal women must also keep in mind that although it becomes less likely, a woman in transition can still become pregnant.
Once a menopausal woman has gone twelve months without a period, the transition is generally considered complete and she enters post-menopause. At this stage, her ovaries have essentially stopped producing estradiol and progesterone, she is no longer ovulating, and can no longer become pregnant. Though this is all part of the normal course of aging, there are some health issues that are associated with menopause and the post-menopausal stage of life:
- Decreased levels of estrogen may lead to an increased risk of osteoporosis.
- The change in the level of estrogen may also be a contributing factor for the development of heart disease.
- Tissues of the vagina tend to thin (atrophy), causing chronic irritation, vaginal dryness, and susceptibility to infection.
- Decreased estrogen level is accompanied with decreased production of collagen and elastin, two proteins responsible for maintaining skin integrity. As these levels decrease, the skin becomes thinner, dryer, and more susceptible to injury.
Menopause happens naturally as a woman ages, but it can also occur for a variety of other reasons. Surgical menopause occurs when the ovaries are removed, such as with ovarian cancer or along with a hysterectomy. Since this removal stops ovary hormone production, it can cause menopausal symptoms to emerge soon after surgery. Menopause can also occur with excessive exposure to radiation or chemotherapy, pituitary gland disorders, or in women with very poor health.
Women who experience menopausal symptoms and hormonal irregularities before the age of 40 were once referred to as having "premature menopause." They are now said to have "premature ovarian failure" or "primary ovarian insufficiency." Some of the women with these conditions may still become pregnant.