Does Breastfeeding Help Prevent Breast Cancer?

Is it true that the longer a woman breastfeeds her babies, the lower her risk of breast cancer? Does it have any other effects on a mother’s long-term health?

– September 29, 2017

Breastfeeding does appear to protect against breast cancer. It is also linked to lower rates of ovarian cancer, type two diabetes, cardiovascular disease, high blood pressure and high cholesterol.

We’ve known for a long time that the more often a woman gives birth, the lower her risk of breast cancer. Research has shown that each birth can reduce a woman’s risk by seven percent and that the risk declines by another four percent for each year a woman breastfeeds her babies. Other research has shown that among women whose mothers or sisters had breast cancer, breastfeeding seems to reduce the risk of the disease by up to 60 percent.

In addition, compared to women who breastfed for a total of 18 months or more, those who never breastfed have a 1.5 percent higher risk of ovarian cancer. Some research suggests that the protective effect here is greatest among women who breastfed their last child.

What’s more, a study from the University of Pittsburgh, published in 2009, found that among 139,681 women participating, those who breastfed for a total of more than 12 months were less likely to develop type two diabetes, high blood pressure, or high cholesterol and were 10 percent less likely to develop cardiovascular disease compared to women who never breastfed.

Research from Harvard and Brigham and Women’s Hospital has shown that the longer a woman breastfeeds, the lower her risk of type two diabetes, regardless of her BMI. Other studies have shown that women who breastfeed have lower rates of postpartum depression and greater weight loss after pregnancy.

All told, the more a women breastfeeds and the longer she continues it, the greater her long-term health benefits. Results of a University of Pittsburgh and Harvard Medical School study published in 2013 showed that if 90 percent of mothers were able to breastfeed for 12 months after each birth, more than 53,000 cases of high blood pressure would be prevented as well as more than 14,000 heart attacks and nearly 5,000 cases of breast cancer. Earlier calculations from the Collaborative Group on Hormonal Factors in Breast Cancer concluded that if women in developed countries had an average of 2.5 children and breastfed each one an extra 6 months, 5 percent of breast cancers would be prevented each year. If they breastfed each child for an additional 12 months, 11 percent of cancers would be prevented annually.

We know that breastfeeding is good for babies, and accumulating evidence suggests that is very good for mothers as well.

Andrew Weil, M.D.


Eleanor Schwarz et al, “Duration of lactation and risk factors for maternal cardiovascular disease.” Obstetrics and Gynecology, May 2009, doi: 10.1097/01.AOG.0000346884.67796

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