Endometriosis is a chronic and incurable gynecological disorder that affects about 10% of women in the United States. Its symptoms can be debilitating and include chronic pelvic pain, painful periods and pain during intercourse. A new study by Brigham and Women’s Hospital investigators found that women who were breastfeeding for longer periods of time had a significantly lower risk of being diagnosed with endometriosis, offering new insights into a condition that had so far had very little known risks and modifiable factors. The team used data from the Nurses’ Health Study II (NHSII), a prospective cohort study begun in 1989. In the current analysis, researchers have followed thousands of women for more than 20 years. During that time, 3,228 women in the study were diagnosed with endometriosis after their first pregnancy. The research team examined how long each woman breast fed, exclusively breastfed (breastfed without the introduction of solid food or formula) and how much time passed before their first postpartum period.
The team found that for every additional three months that mothers breast-fed during pregnancy, women experienced an 8% decline in endometriosis risk. This decrease was even higher for mothers who breastfeed exclusively: the risk of endometriosis fell by 14% for every additional three months of exclusive breastfeeding for pregnancy. The researchers also examined the effects of breastfeeding throughout their reproductive life, ie breastfeeding to more than one child. Women who breastfeed exclusively for 18 months or more during their reproductive life have a nearly 30% lower risk of being diagnosed with endometriosis. The team investigated whether the reduced risk was due to postpartum amenorrhea – the temporary absence of menstrual periods that occur when a woman breastfeeds. They found that this explained some – but not all – of the effect, suggesting that breastfeeding can also influence the risk of endometriosis through other mechanisms.
Breastfeeding modifies many of the hormones in a woman’s body, including oxytocin, estrogen, gonadotropin-releasing hormone, and others for which there is evidence of a role in the pathophysiology of endometriosis. The authors note that although they find a strong association between breastfeeding and a lower risk of endometriosis, they can not untangle if breastfeeding women are less likely to develop the disease. Or if breastfeeding women are less likely to experience symptoms of severe pain enough to indicate a surgical evaluation. The study did not include women who had been diagnosed with endometriosis before their first pregnancy, but researchers are interested in testing whether breastfeeding could help relieve the symptoms of endometriosis for women who have already been diagnosed the illness.
The corresponding author Leslie Farland, a researcher at the BWH Center for Infertility and Reproductive Surgery: “We found that women who breast-fed for a longer duration were less likely to be diagnosed with endometriosis, given the chronic nature of endometriosis and few modifiable risk factors are currently known, breastfeeding may be an important modifiable behavior to reduce the risk of endometriosis among women after pregnancy. Our findings provide support to the body of public and political health that supports the promotion of Breastfeeding Our work has important implications for advising women who are trying to reduce the risk of endometriosis, and we hope that future research will clarify whether breastfeeding could help reduce the symptoms of endometriosis among women that have already been diagnosed”
- edited by Dr. Gianfrancesco Cormaci, PhD, specialist in Clinical Biochemistry.
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