When we think of breastfeeding, we usually think of the benefits for the baby first. Mother’s milk contains vitamins, fat, proteins, and antibodies that provide health benefits to babies later in life. However, babies aren’t the only ones who benefit. It turns out that breastfeeding is good for the mothers too– it helps them to recover from pregnancy and can lower the risk for certain cancers and osteoporosis. A new study from researchers at the University of Pittsburgh has now shown that women who breastfeed their babies for at least six months had better cardiovascular health.

In the study, 678 pregnant women in Michigan enrolled to participate between 1998 and 2004. A follow-up examination was conducted on the same women seven to fifteen years later. The women reported how long they had breastfed for and researchers measured several key factors that are used to assess heart disease risk. They measured blood pressure, cholesterol, triglycerides, and the thickness and diameter of the carotid artery.

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After adjusting for confounding factors such as age, body mass, and socio-economic status, the researchers compared the heart health of women with normal blood pressure during pregnancy. The women who had breastfed for at least six months had much higher levels of “good” cholesterol, lower triglycerides, and healthier carotid artery thickness than the women who had never breastfed. One possible explanation for this result is that breastfeeding increases the expression of the hormone oxytocin, which can lower blood pressure.

“The study adds to the evidence that lactation is important not just for the baby but for the mother,” said Malamo Countouris, MD, a cardiology fellow at the University of Pittsburgh and the study’s lead author. “Breastfeeding seems to be cardioprotective in these women, as evidenced by improved cholesterol and markers of subclinical cardiovascular disease.”

Blood pressure makes a difference. The cardiovascular benefits were only observed for women with normal blood pressure. No cardiovascular benefit was found among women with high blood pressure. However, this result could because the number of participants with high blood may have been too low to show any benefits to these women. Another limitation of the study is that high blood pressure was self-reported by participants and perhaps not completely accurate.

It is promising to know that breastfeeding could have cardiovascular benefits for the mother and is another reason in favor of it. The factors contributing to cardiovascular health in women have been understudied—hopefully, more studies like this one will be conducted to unravel the series of different factors that contribute to heart health in women.