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Moms Who Breastfeed May Be Protected From Type 2 Diabetes
One year of breastfeeding may reduce diabetes risk by 15 percent

BOSTON—The American Academy of Pediatrics recommends that mothers breastfeed infants for at least a year to help a baby’s growth, development and overall health.  Now a study from Brigham and Women’s Hospital (BWH) has found benefits for mothers as well.  Researchers demonstrated that breastfeeding a child for one year may reduce a woman’s risk of developing Type 2 diabetes by 15 percent.  This study appears in the November 23, 2005 issue of the Journal of the American Medical Association.

            “We’ve known for a long time that breastfeeding is good for babies,” said lead author and BWH researcher, Alison Stuebe, MD.  “In this study, we found that it’s good for moms too.”  

            The production of milk requires a breastfeeding mother to use an average of 500 calories each day—the equivalent of running four to five miles.   According to Stuebe, the additional energy required for lactation is associated with short-term changes in insulin, and glucose.  Her study was among the first to look at the long-term association between breastfeeding and incidence of Type 2 diabetes.  “Our study supports the theory that breastfeeding may be associated with important metabolic changes that influence diabetes risk,” she said.  “However more research is needed to determine what hormonal and biological factors are involved.” 

The researchers found that women who breastfed for at least one year were less likely to develop Type 2 diabetes than woman who did not breastfeed.  Specifically, they report:

• One year of breastfeeding was associated with a 15 percent drop in a woman’s risk of developing Type 2 diabetes.  This protective effect appeared to last up to 15 years after a woman’s last birth.

• Each additional year of breastfeeding was associated with a greater reduction in risk.  For example, according to Stuebe, if a woman had two children and breastfed each child for a year, the data suggest that the mother may reduce her risk of diabetes by a third.
• Women with gestational diabetes did not appear to lower their risk of Type 2 diabetes, even if they breastfed intensely. 
• In addition, the data suggest that women who used medications to prevent lactation had an increased risk for Type 2 diabetes. 

“Based on these findings, we have one more reason to encourage mothers to breastfeed,” said Stuebe, who is also a clinical fellow in Obstetrics, Gynecology and Reproductive Biology at Harvard Medical School.  “Ensuring strong support for nursing mothers – from doctors and nurses to family members and employers – isn’t just important for babies.  It’s a women’s health issue, too.”

The study included more than 157,000 nurses who were enrolled in the Nurses’ Health Studies, two cohorts of women who ranged from age 26 to 71 at the start of the study.  The nurses responded to questionnaires regarding how many children they breastfed and for how long, as well as numerous questions about their health, including whether or not they had been diagnosed with Type 2 diabetes by a physician.  The researchers controlled for multiple factors including diet, exercise, weight, and multivitamin use.

For more information, contact BWH Public Affairs at (617) 534-1600 or BWHMediaRelations@partners.org

BWH is a 747-bed nonprofit teaching affiliate of Harvard Medical School and a founding member of Partners HealthCare System, an integrated health care delivery network. BWH is committed to excellence in patient care with expertise in virtually every specialty of medicine and surgery.  The BWH medical preeminence dates back to 1832 and today that rich history in clinical care is coupled with its national leadership in quality improvement and patient safety initiatives, dedication to educating and training health care professionals, and strength in biomedical research. With $370M in funding and more than 500 research scientists, BWH is an acclaimed leader in clinical, basic and epidemiological investigation - including the landmark Nurses Health Study, Physicians Health Studies, and the Women's Health Initiative.  For more information about BWH, please visit www.brighamandwomens.org.