There's a link between breastfeeding and your risk of developing the painful disorder, which affects at least 6.3 million women and girls in the U.S. 

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Breastfeeding isn't just good for your baby: Research suggests the act can lower a woman's risk of heart attack, postmenopausal osteoporosis, obesity and more. Now, we may be able to add endometriosis to that list: A new study finds a link between breastfeeding and decreased risk of the chronic disorder.

Endometriosis can cause painful periods and intercourse, and it affects about 10 percent of women in the United States. Until now, there haven't been many scientifically proven ways to reduce endometriosis risk—but according to research published in the The British Medical Journal (BMJ), women who breastfeed for a greater duration have lower chances of being diagnosed with the condition.

The researchers studied a group composed of thousands of women for over 20 years—and 3,296 of those women were surgically diagnosed with endometriosis. They also observed data collected from the Nurses' Health Study, which began in 1989.

A relationship between breastfeeding habits and endometriosis risk emerged: The researchers found that for every three months a woman nursed, her endometriosis risk declined by 8 percent. Among mothers who exclusively breastfed, the drop was 14 percent for every three months of breastfeeding. Nursing multiple children also showed a positive effect, as it added to the total number of months each woman spent breastfeeding—women who nursed exclusively for at least 18 months had a 30 percent reduction in risk.

The researchers behind this study aren't quite sure how this link works. While they initially theorized that postpartum amenorrhea (the absence of menstrual periods in the postpartum period) may be at the root, they realized that this is only part of the equation, and that other mechanisms likely contributed to this link. While this study only included women who were diagnosed with endometriosis in the postpartum period, researchers are curious as to whether breastfeeding could reduce symptoms in those who were diagnosed before getting pregnant.

“We found that women who breastfed for a greater duration were less likely to be diagnosed with endometriosis. Given the chronic nature of endometriosis and that very few modifiable risk factors are currently known, breastfeeding may be an important modifiable behavior to reduce the risk of endometriosis among women after pregnancy," said corresponding author Leslie Farland, according to a Brigham and Women's Hospital release. “Our work has important implications for advising women who are looking to lower their risk of endometriosis. We hope that future research will illuminate whether breastfeeding could help lessen the symptoms of endometriosis among women who have already been diagnosed.”