Women who breastfed for longer periods of time had significantly lower risk of being diagnosed with endometriosis -- a gynecologic disorder characterised by chronic pelvic pain and painful periods, according to researchers.
The findings showed that for every three additional months that mothers breastfed per pregnancy, women experienced an eight per cent drop in risk of endometriosis.
Further, women who breastfed exclusively for 18 months or more across their reproductive lifetime had a nearly 30 per cent lower risk of being diagnosed with endometriosis.
"We found that women who breastfed for a greater duration were less likely to be diagnosed with endometriosis," said Leslie Farland, a research scientist at the Brigham and Women's Hospital in the US.
"Given the chronic nature of endometriosis and that very few modifiable risk factors are currently known, breastfeeding may be an important modifiable behaviour to reduce the risk of endometriosis among women after pregnancy," Farland added.
For the study, published in the journal The BMJ, the team analysed 3,296 women who 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 post-partum period.
Although for some, the decreased risk was found to be due to post-partum amenorrhea -- the temporary absence of menstrual periods that occurs when a woman is breastfeeding.
However, for others, breastfeeding was found to influence endometriosis risk through other mechanisms.
Breastfeeding changes many of the hormones, including oxytocin, estrogen and gonadotropin-releasing hormone besides others, in a woman's body, the researchers said.
"Our work has important implications for advising women who are looking to lower their risk of endometriosis and may lend support to the body of public health and policy literature that advocates promotion of breastfeeding," Farland said.