Scientists have found a way to predict approximately when menopause will occur, according to a new study being presented by Dr. Aimee Eyvazzadeh, Sunday, June 15, at The Endocrine Society’s 90th Annual Meeting in San Francisco.

A research team, led by MaryFran Sowers, PhD, professor of epidemiology at the University of Michigan, found that a low level of a certain hormone may help identify when a woman will have her final menstrual period 4 to 5 years before it ends. This information is useful for perimenopausal women and for women considering pregnancy later in life, said Sowers.

“Many women want to know when menopause will start, when it will end, and how disruptive it will be,” Sowers said. “It’s empowering for a woman to know what her current reproductive status is.”

The age at menopause in the Western world is most often 51 but varies widely among women, according to Sowers. Until now, scientists have had limited success in predicting when a woman’s period would stop. They typically estimate it based on a woman’s body type, lifestyle factors such as smoking, and when her mother went through menopause.

It is already known that two hormonal markers of ovarian aging, anti-Muellerian hormone (AMH) and inhibin-B, decrease as a woman approaches menopause. Therefore, the Michigan researchers evaluated whether levels of these two hormones in a woman’s blood could predict the timing of her last period. Over the course of 6 years they measured levels of these hormones in 50 women who enrolled in the Michigan Bone Health and Metabolism Study in 1992, gave blood samples annually and later had a documented final menstrual period. Women had an average age of 41 when they started the study. The authors also evaluated whether smoking or body mass index (BMI) affected the findings.

Results showed that a woman’s AMH level became very low or undetectable 4 to 5 years before her final period. Smokers had earlier declines in their AMH level than women who did not smoke, which is consistent with the fact that smokers reach menopause at a younger age, Sowers said. Women with higher BMI also had earlier declines in AMH compared with women who weighed less. Unlike AMH, inhibin-B did not consistently predict the time to the last period.

Sowers cautioned that AMH cannot predict the onset of menopause to within 1 or 2 years. An undetectable AMH level simply means that a woman has a high probability of experiencing menopause in 4 to 5 years, she explained. AMH is a natural product of follicles produced in the ovaries.

“There is a whole series of events and processes to the final menstrual period,” Sowers commented. “This hormone is a marker of where women are likely to be in that process. It’s like having a yardstick for ovarian aging.”

Past studies showed that this hormone marker does not have the same variability through the menstrual cycle that is typical of many other hormones. Therefore, doctors can measure it at any time of the month without having to factor in where the woman is at in her cycle, Sowers said.

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Founded in 1916, The Endocrine Society is the world's oldest, largest, and most active organization devoted to research on hormones and the clinical practice of endocrinology. Today, The Endocrine Society's membership consists of over 14,000 scientists, physicians, educators, nurses and students in more than 80 countries. Together, these members represent all basic, applied, and clinical interests in endocrinology. The Endocrine Society is based in Chevy Chase, Md. To learn more about the Society, and the field of endocrinology, visit our web site at www.endo-society.org.