Women with normal blood pressure during pregnancy may be able to reduce their risk of heart disease by breastfeeding for at least six months per birth, according to new research that will be presented at the American College of Cardiology’s 67th Annual Scientific Session.
Heart disease is the leading cause of death for women in the United States. High blood pressure, high LDL cholesterol and smoking are risk factors for heart disease and, according to the CDC, about half of Americans have at least one of those three risk factors.
"There’s a lot we still don’t understand about the accumulation of cardiovascular risks in women," said Dr. Malamo Countouris, a cardiology fellow at the University of Pittsburgh and the study’s lead author, in a press release. "Examining how pregnancy may increase or perhaps mitigate some of that risk can give us insights into the unique presentation and development of heart disease risk in women."
The study enrolled 678 women from various clinics across the state of Michigan during their pregnancies, between 1998 and 2004. After an average of 11 years, the women participated in a follow-up health assessment, and were asked how long they breastfed after each pregnancy. At the same time, researchers measured the women’s blood pressure, cholesterol, triglycerides, and the diameter and thickness of the carotid artery — factors commonly used to assess heart disease risk.
After the researchers said they adjusted for factors that could distort the results, they say they found that women who had normal blood pressure during pregnancy and who breastfed for six months or more had significantly higher levels of HDL (“good” cholesterol), lower triglycerides and healthier carotid artery thickness, compared to those who had never breastfed.
Since this is a meeting presentation, the study hasn’t been through the peer review process that leads to publication in a medical journal. Some questions that might be asked: if the group of pregnant women studied was older, thinner, or more educated, that might make the group more likely to exercise, eat wisely, and not smoke. Those are also factors that influence heart health.
The reason for these results? Unknown. Some theories exist, including breastfeeding increases the hormone oxytocin, which can lower blood pressure, and that breastfeeding could counteract some of the metabolic changes that occur during pregnancy.
According to Countouris, this new study "adds to the evidence that lactation is important not just for the baby but for the mother."