Menopause is the time in a woman’s life when the function of the ovaries ceases. The ovary, or female gonad, is one of a pair of reproductive glands in women. They are located in the pelvis, one on each side of the uterus. Each ovary is about the size and shape of an almond. The ovaries produce eggs (ova) and female hormones such as estrogen. During each monthly menstrual cycle, an egg is released from one ovary. The egg travels from the ovary through a fallopian tube to the uterus.
The ovaries are the main source of female hormones, which control the development of female body characteristics such as the breasts, body shape, and body hair. The hormones also regulate the menstrual cycle and pregnancy. Estrogens also protect the bone. Therefore a woman can develop osteoporosis (thinning of bone) later in life when her ovaries do not produce adequate estrogen.
Menopause does not occur overnight, but rather is a gradual process of transition. This transition period (known as perimenopause) is different for each woman. Scientists are still trying to identify all the factors that initiate and influence this transition. Women in perimenopause transition typically experience abnormal vaginal bleeding such as erratic periods or abnormal bleeding patterns. Eventually a woman’s periods will completely stop as she completes this transition into menopause.
The average age of onset of menopause process is 51 years old. But there is no single method to predict when a woman will enter menopause. The age at which a woman starts having menstrual periods is also not related to the age of menopause onset. As a rough “rule of thumb” women tend to undergo menopause at an age similar to that of their mothers.
When does a woman know she is in menopause?
A woman is in menopause if she has had no menstrual periods (menses) for 12 months and has no other medical reason for her menses to stop. That means she has to be evaluated by her doctor to exclude other medical causes of missed menses.
Are hormone levels or other blood tests helpful in detecting menopause?
Because hormone levels may fluctuate greatly in an individual woman, even from one day to the next, hormone levels are not a reliable indicator for diagnosing menopause. Even if levels are low one day, they may be high the next day in the same woman. There is no single blood test that reliably predicts when a woman is going through menopause, or menopausal transition. Therefore there is currently no proven role for blood testing regarding menopause except for tests to exclude medical causes of erratic menstrual periods other than menopause. The only way to diagnose menopause is to observe lack of menstrual periods for 12 months in a woman in the expected age range.
Revision date: July 5, 2011
Last revised: by Janet A. Staessen, MD, PhD