Low BMI May Increase Risk For Endometriosis
May 15, 2013

Endometriosis Risk May Be Higher For Those Women With A Below Average BMI

Brett Smith for redOrbit.com - Your Universe Online

While the condition is not recommended by physicians, “morbidly obese” women were found to have a lower risk of endometriosis than much thinner women, according to a new study in the journal Human Reproduction.

The comprehensive study included over 100,000 women and found that those with a body mass index (BMI) greater than 40 kg per square meter had a 39 percent lower risk of contracting the painful gynecological condition than women with a BMI between 19 and 22 kg/m2, considered to be low-normal.

"We have consistently seen previous data over the years demonstrating a relationship between inverse BMI and endometriosis risk,” Heather Guidone, Surgical Program Director of the Center for Endometriosis Care, said in response to the new study. “In fact, at least one prior study indicated patients with the lowest BMI were at the highest risk for the most severe form of disease (deeply infiltrating).”

“Now with more than 20 years of data on over 100,000 women, this is the largest prospective study to date clarifying this persistent trend,” she added.

In their report, the authors said that the strongest connection between BMI and endometriosis risk was found in infertile women. For women who had unsuccessfully been trying to become pregnant for more than a year, the study´s most obese women had a 62 percent lower rate of endometriosis than those with a low to normal BMI.

The researchers used data from the Nurses' Health Study II (NHS II), which included over 110,000 female nurses who were followed from September 1989 to June 2011.

During the 20-year span of the study, just over 5500 women were diagnosed with endometriosis. These women were in the prime reproductive years, between 25 and 42 years of age, when the study began in 1989. The participants were first asked to complete a survey about their medical history when they joined the program and then at two-year intervals after that.

"Analysis of the first ten years of NHS II data revealed an inverse relation between endometriosis and BMI at age 18 among all women, and, in a subset of infertile women, an inverse relation between endometriosis and current BMI,” said senior author Stacey Missmer, an associate professor at Harvard Medical School. “This study confirms that women with a low BMI, both currently and at age 18, have a greater risk of developing endometriosis. The association remains stronger in infertile women, but is present in all women regardless of fertility status.”

"Insomuch as any data can ever claim to be definitive, we do believe that this large prospective study provides conclusive evidence of the inverse association between endometriosis and BMI,” she added.

“Certainly, more investigation is needed, and we have to be careful not to jump to any conclusions which would cause us to dismiss women with potential endometriosis diagnoses - simply because they don´t fit the ℠low BMI´ criteria; but this is a simple clinical parameter to consider along with other factors,” Guidone said. “Endometriosis remains so poorly understood and the delay in diagnosis continues to range upwards of a decade, so it´s encouraging to see progress unfolding on the biologic factors contributing to the disease.”

“This latest study lends hope to that idea that some day we may be better able to define and target specific research, which will translate into real-time bench to bedside results“¦and possibly one day, even prevention of endometriosis,” she added.