The longer mothers breastfed, the greater the benefit.
New research suggests children aren’t the only ones who benefit from breastfeeding. Mothers may see long-term health benefits too. Researchers from China and the UK analyzed data from hundreds of thousands of women over eight years. They found that mothers who had breastfed their children were nine percent less likely to have heart disease and eight percent less likely to have experienced a stroke than those who didn’t. We spoke with study author Sanne Peters, an epidemiologist at Oxford University, to learn more.
ResearchGate: What led you to investigate the heart health benefits of breastfeeding for mothers?
Sanne Peters: Breastfeeding has major benefits for child health. Previous studies have suggested that mothers get short-term health benefits from breastfeeding too, like weight loss, lower cholesterol, and blood pressure levels after pregnancy. However, the effects of breastfeeding on the mother’s risk of cardiovascular disease later in life are unclear.
RG: What did you find?
Peters: Mothers who had breastfed their babies had a nine percent lower risk of heart disease and an eight percent lower risk of stroke compared to mothers who had never breastfed. Each additional six months of breastfeeding per baby was associated with a four percent lower risk of heart disease and a three percent lower risk of stroke. These results were broadly consistent across different age groups and regions and persisted after adjustment for a range of sociodemographic and lifestyle-related factors that may also be related to a woman’s risk of heart disease and stroke.
“Mothers who had breastfed their babies had a nine percent lower risk of heart disease and an eight percent lower risk of stroke.”
RG: How did you determine this?
Peters: We analyzed the data of 289,573 Chinese women aged 30 to 79 participating in the China Kadoorie Biobank study. These women had provided detailed information about their reproductive history and other lifestyle factors. Nearly all were mothers, and none had cardiovascular disease when they enrolled in the study. After eight years of follow-up, there were 16,671 cases of coronary heart disease (including heart attacks), and 23,983 stroke cases. These data allowed us to study the relationship between breastfeeding and the risk of heart disease and stroke, and to adjust for other factors like age, smoking, high blood pressure, physical exercise, overweight and obesity, and diabetes.
RG: What do you think explains the associations you found?
Peters: Our study was not designed to prove cause and effect. However, if they are causal, the health benefits to the mother from breastfeeding may be explained by a faster “reset” of the mother’s metabolism after pregnancy. Pregnancy causes major changes to a woman’s metabolism as she stores fat to provide the energy necessary for her baby’s growth and for breastfeeding once the baby is born. Breastfeeding could eliminate the stored fat faster and more completely. However, women who breastfeed may also be more likely to engage in other beneficial health behaviors than women who do not breastfeed. While this is the case in Western populations, this pattern was not seen in our study. Instead, we found that poorer women from rural areas of China were more likely to breastfeed for longer periods than their wealthier urban counterparts. Further studies will be needed to confirm the present findings and to identify the mechanisms involved.
“Pregnancy causes major changes to a woman’s metabolism as she stores fat to provide the energy necessary for her baby’s growth and for breastfeeding.”
RG: What are typical breastfeeding practices in China?
Peters: Breastfeeding is almost universal in China, and many women continue to breastfeed their infants for long durations, particularly in older generations. Breastfeeding practices of Chinese women have changed significantly over the past several decades, with declines in both the likelihood to start breastfeeding and the duration of breastfeeding. These changes are partly or wholly due to the major social and economic changes that have occurred in China. In 2008, fewer than 16 percent of urban, and around 30 percent of rural, women exclusively breastfed their babies throughout the World Health Organization’s recommended period of six months.
RG: Would you expect similar findings in the US and Europe?
Peters: Although we can’t extrapolate these findings to other settings, they are consistent with studies conducted with Western populations. Results from the US Nurses’ Health Study and European EPIC-CVD study have also shown that a history of breastfeeding was associated with lower risk of coronary heart disease later in life, particularly among those who breastfed for longer periods. So while breastfeeding practices differ both within and across countries and cultures, there is no evidence that such differences had a major impact on our findings.
RG: Should these results factor into mothers’ decisions about breastfeeding?
Peters: Our findings suggest that breastfeeding confers benefits for maternal cardiovascular health, independent of other risk factors. While the findings of our study do not negate the importance of a healthy lifestyle choices—such as healthy diet, sufficient exercise, and non-smoking—the take-home message is that breastfeeding is associated with a lower risk of cardiovascular disease and that longer durations may provide additional benefits.