A recent study by Brigham and Women’s Hospital (BWH) investigators found that women who breastfed for longer periods of time were less likely to develop endometriosis. These findings offer new insights into a condition that has had very few known, modifiable risk factors. The findings were published in The BMJ.
“We found that women who breastfed for a greater duration were less likely to be diagnosed with endometriosis,” says Leslie Farland, ScD, a research scientist at the Center for Infertility and Reproductive Surgery. “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.”
The team used data from the Nurses’ Health Study II (NHSII), which began in 1989. In the analysis, they followed thousands of women for more than 20 years. During that time, more than 3,000 women in the study were surgically diagnosed with endometriosis after their first pregnancy. The research team examined how long each woman breastfed, exclusively breastfed (breastfed without the introduction of solid food or formula), and how much time passed before their first postpartum period.
Results showed that for every three additional months that mothers breastfed per pregnancy, women experienced an eight percent drop in risk of endometriosis. This drop was even higher for mothers who exclusively breastfed: Risk of endometriosis dropped 14 percent for every three additional months of exclusive breastfeeding per pregnancy.
The researchers also looked at the effect of breastfeeding across reproductive lifetime – that is, breastfeeding more than one child. Women who breastfed exclusively for 18 months or more across their reproductive lifetime had a nearly 30 percent lower risk.
“Our findings lend support to the body of public health and policy literature that advocates for the promotion of breastfeeding,” says Farland. “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.”