There is not complete agreement about the meaning and use of terms that are used regarding menopause. The term menopause itself has different meanings, and there are other terms such as menopausal transition, perimenopause, postmenopause, and climacteric that are used in different ways by different people.

While many people nowadays use the term menopause to mean a period of time, such as "during the menopause" or "going through the menopause," the medical definition of menopause is a single date. Menopause is the first day of the last bleeding episode (menstrual period) of a woman's life.

There are different causes of menopause. Natural menopause occurs because of decreases in the workings of the ovarian follicles (each follicle is a groups of cells in the ovary that has an egg or ovum in the center). The decreases are related to changes over time in the ovary.

Menopause also occurs after surgical removal of the uterus -- hysterectomy -- and/or surgical removal of the ovaries -- oophorectomy. Surgical menopause is when both the uterus and ovaries are removed. In the case of hysterectomy without removal of the ovaries, a woman cannot have uterine bleeding or spotting (menstrual periods) because she no longer has a uterus, but her ovaries will continue on their natural changes over time; the woman will just not have any signs of those changes in bleeding patterns. Menopause can also be caused by loss of the working of ovarian follicles such as occurs with chemotherapy or radiation, or sometimes with medical problems, such as hypothyroidism.

When researchers use the term menopausal transition it usually means the period of time before menopause when women experience changes in their bleeding and spotting.

When researchers use the term perimenopause it usually means the menopausal transition plus the first 12 months (first year) after the exact date of menopause.

When researchers use the term postmenopause, it usually means the remainder of a woman's life after menopause. It may be confusing, however, because some researchers use the term postmenopause to mean the time after the perimenopause, that is, the rest of a woman's life starting one year after the first day of her last bleeding episode (menstrual period).

For more about how our study has contributed to a refinement of these definitions, click on What We Have Learned.