Obese women can be more likely to have heavy monthly periods and experience fibroid growth, and now new research hints at why.
In addition to stirring up inflammation, excess weight may slow down the uterine repair process, U.K. researchers reported. Menstruation occurs when the lining of the uterus (endometrium) sheds each month, but the healing process stops the bleeding so the lining can build back up.
Heavy periods — defined as needing to change your tampon or pad after less than two hours and/or passing large blood clots — can take a dramatic toll on a woman’s quality of life, says study author Dr. Jacqueline Maybin, a researcher at the MRC Centre for Reproductive Health at the University of Edinburgh.
“Some people have such heavy periods that they can’t leave the house when menstruating as they flood through their menstrual products onto their clothes,” she shares. “This results in work or school absence, an increased financial burden due to paying for extra menstrual products and an inability to carry out caring roles.”
When Maybin and her colleagues measured the body mass index (BMI) and menstrual blood loss of 121 women with regular menstrual cycles, they found that as BMI increased, so did menstrual blood loss. (BMI is a measure of weight in relation to height.) The relationship was weak, but still statistically significant after controlling for other factors that may affect blood loss during menstruation, she says.
The team conducted a companion study in mice to get a better handle on why higher BMIs might cause heavier periods. Mice fed a high-fat diet had significantly greater body weight than those on a normal diet. After shedding their uterine lining, the mice on a high-fat diet showed delayed repair of the remaining lining and greater levels of inflammatory markers than mice on a normal diet did.
Dr. Andrea Dunaif is a professor of medicine at the Icahn School of Medicine at Mount Sinai and chief of the Division of Endocrinology, Diabetes and Bone Disease at the Mount Sinai Health System in New York City. The new findings mirror what she sees in her practice.
Heavy and irregular periods are more common in women with higher BMIs, Dunaif says.
Dr. Michael Jensen, an endocrinologist at the Mayo Clinic in Rochester, Minn., was skeptical about the new findings.
“Women, as they get heavier, are more prone to heavy periods, but the mouse model is hard to link back to women,” Jensen notes. Weight loss may help reduce blood loss during menstruation, but more research is needed to fully understand why and how obesity affects menstruation in overweight or obese women, he says.
The importance of weight loss
More research is needed to confirm the findings, but weight loss and anti-inflammatory medications may lighten