The advantages of breastfeeding have been extolled for decades, with piles of research demonstrating the nutritional qualities of breastmilk and the far-reaching health benefits for both mother and baby. Recently, a systematic review of eight studies examining breastfeeding and cardiovascular risk turned up results that add to the existing positives for people who choose to breastfeed, including reduced diabetes, breast cancer and ovarian cancer risks.
Cardiovascular disease is the leading cause of death globally, the leading killer of women in the United States and the primary killer of Black women, a population already at increased risk of poor maternal health outcomes. Learning ways to reduce the risks is paramount to improving maternal heart health.
What the data shows
Researchers analyzed data from eight studies including more than 1 million people who have given birth, with an average of 2.3 babies per parent. A total of 82 percent of the subjects reported having breastfed, for an average of 15.6 months. The number of heart-related health events for the participants was recorded during a 10-year follow-up.
The analysis found people who breastfed had an 11 percent lower risk of developing cardiovascular disease than those who never breastfed. People who breastfed also reduced their risk of developing coronary heart disease by 14 percent, stroke by 12 percent and death from cardiovascular disease by 17 percent.
Breastfeeding for a year or more led to better maternal heart health.
"This is yet another long-term maternal benefit to those who are able to breastfeed for at least 12 months during their lifetime, meaning it can be spread across multiple children, not just one," explained Shannon Schellhammer, M.D., an OB-GYN at Orlando Health Winnie Palmer Hospital for Women & Babies.
Examining the breastfeeding-cardiovascular connection
"This is a fascinating and groundbreaking study. Research has always delved for the most part into health benefits for the baby, but not so in depth for the mother, specifically, the cardiovascular benefits," said Kecia Gaither, M.D., who is board-certified in OB-GYN and maternal-fetal medicine and the director of perinatal services/maternal-fetal medicine at NYC Health + Hospitals/Lincoln in the Bronx in New York City.
While one specific physiological process has been identified, this study review shows that several other causes contribute to the cardiovascular health benefits of lactation. Gaither helped unpack the potential factors.
Hormonal factors during lactation
Different hormones are at play during lactation, specifically, prolactin and oxytocin.
"While the effect of prolactin has had conflicting results in various research studies concerning cardiovascular benefits, it has been deemed that oxytocin has a marked beneficial effect on the cardiovascular system," Gaither explained.
Oxytocin, most associated with feel-good effects, also lowers blood pressure, provides vasodilatory effects, lowers fat mass, inhibits inflammation and has antioxidant benefits—all of which help to reduce the development of cardiovascular disease.
Lactation resets metabolism
"Lactation resets maternal metabolism; it has an antidiabetogenic effect and diminishes hyperlipidemia," Gaither said.
During normal pregnancy, some detrimental metabolic effects develop, increasing the risk of cardiometabolic disease. These risks can be offset by lactation, but an elevated risk remains when it does not occur. Researchers believe lactation is part of a natural continuum that has evolved to reset the metabolism.
In other words, by breastfeeding, you may protect yourself against diabetes and high cholesterol, which can lead to cardiovascular disease. This is especially significant for females since the risk of heart attack due to diabetes is almost 50 percent greater in females than in males.
Longer breastfeeding increases benefits
"The degree of atherosclerosis—damage to vessel linings—is inversely correlated to the length of time breastfeeding, so the more time you breastfeed, the lesser the degree of damage," Gaither said.
Researchers discovered from the meta-analysis that cardiovascular risk was progressively reduced for lifetime durations of breastfeeding up to 12 months; the longer subjects reported breastfeeding, the more benefit they saw for heart health. Researchers didn't examine longer durations of breastfeeding, so it's difficult to tell if benefits extend beyond 12 months.
Breastfeeding encourages healthy weight balance
"Breastfeeding allows for more rapid weight loss, obesity being a risk factor for cardiovascular disease," Gaither explained.
Breastfeeding could be helpful in assisting postpartum body mass reduction and, thus, cardiovascular risk.
Of course, it is possible to be heart-healthy at a higher weight, but research indicates obesity increases the risk of developing cardiovascular disease. While actively trying to lose weight while breastfeeding certainly is not recommended, lactation can encourage your body to naturally obtain a healthy weight balance.
What are the implications?
Cardiovascular diseases are the No. 1 global cause of death. Breastfeeding may provide protective benefits for maternal heart health, with effects increasing the longer lactation occurs. However, only a quarter of infants are exclusively breastfed for the first six months of life, despite recommendations from the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC).
According to the CDC, Black infants are even less likely than white infants to be breastfed at all. Maternal health outcomes for Black parents are already worse than outcomes for white parents. Of course, heart disease is the leading cause of death for women of all races and origins.
The results of this meta-analysis show a pressing need for education through public health organizations, media and health systems around not only the health benefits of breastfeeding for the baby, but also for the mother.
"This is groundbreaking research which I believe has opened the door to evaluating multiple methods for decreasing cardiovascular disease in women and, ultimately, decreasing the mortality rate due to it," Gaither said.
Gaither also believes the scientific community should do further research on the interplay of hormonal changes after birth.
"This facet could be an area wide open for research. Perhaps medications could be formulated to mimic these hormonal alterations, leading to a reduction in cardiovascular risk," she explained.
This possibility is particularly important for women who aren't able to breastfeed, as well as women who could benefit by virtue of their age, body mass index (BMI) or underlying comorbidities for cardiovascular disease.
"This current article is one of the highest scientific strengths as it looked at all the research available in the interaction between breastfeeding and maternal cardiovascular risk," Schellhammer said. "As a society, we should recognize these benefits and encourage and support mothers to breastfeed as it will lead to better health outcomes in the future."