The latest large scale study of almost 80,000 women concludes that being underweight poses a risk of experiencing early menopause.
The new study were led by Dr. Kathleen Szegda — who, at the time of the study,was a postdoctoral research associate at the University of Massachusetts in Amherst — and the findings were published in the journal Human Reproduction.
Commonly menopause is a normal condition that all women experience as they age. The term "menopause" can describe any of the changes a woman goes through either just before or after she stops menstruating, marking the end of her reproductive period.
Dr. Szegda and her team started from the observation that high and low levels of fat have been linked with reproductive function in previous studies. They therefore hypothesized that how much a woman weighs may also affect when she experiences menopause.
For the testing of this theory, the researchers analyzed data on 78,759 women from the Nurses' Health Study II, and they clinically followed them between 1989 and2011. The women were aged 25–42 years, and the researchers gathered information on their height, weight, and menopausal status using a questionnaire.
Furthermore,this information, along with data on hormone therapy use, was gathered and updated every two years. Additionally, information was gathered on the participants' teenage years.
And for the findings, "early menopause" was defined as occurring before a woman reaches 45. The team used multiple regression models to assess early menopause risk, and overall, 2,804 women in the study reported having experienced it.
Body weight below BMI raised early menopause risk by 30 percent
According to the National Institutes of Health (NIH) a weight between 18.5 and 24.9 kilograms per square meter to be normal, while women who weigh less than that are considered to be underweight.
In this large study, women with a body mass index (BMI) below 18.5 kilograms per square meter — at any age — were 30percent more likely to experience early menopause compared with women whose BMI was between 18.5 and 22.4 kilograms per square meter.
The study team also found that women whose BMI was between 25 and 29.9 kilograms persqaure meter were up to 30 percent less likely to experience early menopause.
Again the team noted, the highest likelihood of having early menopause seemed to be among women who, when they were 18 years old, had a BMI below 18.5 kilograms persqaure meter and reported having experienced "severe weight cycling."
Lastly, women who had a BMI lower than 17.5 kilograms per square meter at the age of 18were 50 percent more likely to have an early menopause compared with normal-weight women.
Being underweight may have an impact on the timing of menopause
Dr. Szegda sums up the findings, saying, "Women who are underweight in early or mid-adulthood may be at increased risk for early menopause."
This is "associated with a higher risk of cardiovascular disease, and other health conditions such as cognitive decline, osteoporosis, and premature death,so these findings have important implications for women and their doctors," she explains.
Dr. Szegda adds that 10 percent of women experience early menopause, and that"underweight women may want to consider discussing the potential implications of these findings with their doctors."
"Causes of early menopause are not clearly understood," she continues. However:
"Our findings suggest that being underweight may have an impact on the timing of menopause. More research is needed to understand how it increases the risk of early menopause." Dr. Kathleen Szegda
The team also admits some limitations in their study. "It is possible that underweight women may have been misclassified with an earlier age at menopause if being underweight led to amenorrhea (i.e., the absence of menstruation),"they write.