Breastfeeding helps prevent endometriosis

Stephen Padilla
04 Sep 2017
Breastfeeding helps prevent endometriosis

An inverse relationship exists between breastfeeding and risk of incident endometriosis among women who experienced at least one pregnancy that lasted at least 6 months, according to a recent study. Postpartum amenorrhoea partially, but not fully, influences such association, suggesting that breastfeeding may affect the risk of endometriosis both through amenorrhoea and other mechanisms.

“The strong inverse relation we found between duration of breastfeeding and risk might have important clinical implications for advising women to modify their risk profile for endometriosis. Our findings lend support to the body of public health and policy literature that advocates for the promotion of breastfeeding,” researchers said.

“All women should be counseled regarding the health benefits of breastfeeding for both the mother and child, systems level policy changes should be implemented to encourage breastfeeding, and future research should investigate the benefit of breastfeeding among women diagnosed with endometriosis for symptom control,” they added.

Total and exclusive breastfeeding significantly correlated with decreased risk of endometriosis. There were 453 endometriosis cases per 100,000 person-years among women who reported a lifetime total length of breastfeeding of <1 month compared with 184 cases per 100,000 person-years in women who reported a lifetime total of ≥36 months of breastfeeding. [BMJ 2017;358:j3778]

Each additional 3 months of total breastfeeding per pregnancy resulted in an 8-percent lower risk of endometriosis (hazard ratio [HR], 0.92; 95 percent CI, 0.90 to 0.94; p<0.001 for trend), and each additional 3 months of exclusive breastfeeding led to a 14-percent lower risk (HR, 0.86; 0.81 to 0.90; p<0.001 for trend).

Breastfeeding for ≥36 months in total across women’s reproductive lifetime resulted in a 40-percent reduced risk of endometriosis compared with those who never breastfed (HR, 0.60; 0.50 to 0.72). This protective association with breastfeeding was strongest among women who gave birth within the past 5 years (p=0.04 for interaction).

Furthermore, postpartum amenorrhoea partially influenced the association between endometriosis and total (% mediated, 34 percent; 15 to 59 percent) and exclusive (% mediated, 57 percent; 27 to 82 percent) breastfeeding.

“Our findings confirm previous reports of an inverse relation between breastfeeding and risk of endometriosis. In previous research within our cohort, with 6 years of follow-up and 448 incident cases, we reported a significant relation between a one-time measure of lifetime duration of breastfeeding and endometriosis (p=0.008 for linear trend). [Obstet Gynecol 2004;358:965-74; Environ Res 2007;358:121-9]

In this prospective cohort study, the investigators identified a total of 72,394 women who reported having one or more pregnancies that lasted at least 6 months. Of these, 3,296 had laparoscopically confirmed endometriosis. For each pregnancy, women reported duration of total breastfeeding, exclusive breastfeeding and postpartum amenorrhoea.

“Endometriosis is a chronic disease with no known cure and debilitating symptoms. At present, few modifiable risk factors are known to prevent its occurrence. Future research should investigate breastfeeding as a mechanism for mitigation of symptoms among women with a diagnosis of endometriosis,” according to researchers.

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