03/26/2013 12:50 pm ET

Last Menstrual Cycle Could Be Predicted With New Model (STUDY)

A new method for predicting a woman's last menstrual cycle could have broader implications for menopausal women's health by helping fight bone loss and the risk of heart disease, a new study reports.

Researchers at the University of California have come up with a formula using the levels of two hormones to estimate when a woman's last menstrual cycle will take place. The formula relies on changing levels of estradiol, a hormone present in the ovary, and follicle stimulating hormone, a hormone in the brain that give instructions to the ovaries. When women go through menopause, follicle stimulating hormone levels go up while estradiol levels go down.

Typically, doctors study women's menstrual bleeding patterns to determine the so-called transition phase, even though it's an imperfect way to figure out when the final menstrual period will happen, according to the authors of the study published in the April issue of the Journal of Clinical Endocrinology & Metabolism. More than 60 percent of women who are classified as early perimenopausal -– meaning that their periods are irregular but they have no huge gaps in cycles -– become postmenopausal without any additional clinical bleeding signal.

"We need a better way to answer women's questions about when to expect the final menstrual period," lead author Dr. Gail Greendale, of UCLA's David Geffen School of Medicine, said in the news release.

The researchers analyzed longitudinal data from 554 women taking part in the National Institutes of Health's Study of Women's Health Across the Nation to develop their new formula for pinpointing a woman's last period.

Being able to predict the last menstrual cycle could also impact women's health in general, Greendale said. In the year leading up to the final menstrual period, women are met with faster bone loss and a greater risk of heart disease.

"For example, some researchers have proposed that an intervention begun one or two years before the final menstrual period would greatly decrease future fracture risk by preventing the very rapid bone loss that occurs in the few years before and few years after the final menses," Greendale said. "But before ideas such as this can be tested, we need to accurately predict where a woman is in her timeline to menopause."