Obese Women Have Lower Risk of Endometriosis

A new study says that thin women are more likely to develop endometriosis than obese women. The risk for the condition was 39 percent lower in women who were obese.

Endometriosis affects a woman's uterus and usually causes infertility. In this condition, the tissue that's supposed to be lining the uterus starts growing on other parts, such as the ovaries, bowels or bladder.

In the present study, researchers found that women who were obese, around 18 years of age, had a 41 percent lower risk of developing the condition than other women.

The data for the study came from the Nurses' Health Study II (NHS II) - a study that has followed over 116,430 female nurses in the U.S. since 1989. Over the course of 20 years, more than 5,500 women were diagnosed with endometriosis.

The link between obesity and endometriosis was the strongest in infertile women. These women had a 62 percent lower rate of developing the condition, while there was a 70 percent lower rate of the condition in women who were obese when they were in their teens.

Women who are obese at a younger age have an increased risk of polycystic ovarian syndrome (PCOS), and the effects of this syndrome might be lowering the risk of endometriosis in obese women, researchers said.

Researchers caution that obesity is a major health issue. "The study does not suggest that the morbidly obese women are, in some way, healthier than the lean women and that is the reason for their lower risk of endometriosis. It is more likely that factors related to infertility, which is more common among the very obese, are linked to the reduced risk of endometriosis," Divya Shah (MD), at the University of Iowa Hospitals and Clinics, said in a news release. Shah is the first author of the study.

The study is published in the journal Human Reproduction.