The list of benefits of breastfeeding is only growing longer. We have known for a long time now that breastfeeding reduces the risk of heart attacks, high blood pressure, diabetes, and metabolic syndrome for mothers later in life. A fascinating new study draws on a large cohort of women followed over 20 years.
2,787 women were a part of the CARDIA study in 1985-86 when they were 18-30 years of age. Extensive metrics were collected on these women including obstetric and cardiovascular histories and measures. Twenty years later, 2,014 women completed the follow up examination. For this study, the authors isolated 846 of these women who did not have heart disease or diabetes at the start of the study and who had at least one pregnancy and delivery since enrolling in the study. The researchers collected a number of metrics to establish cardiovascular risk such as cholesterol, blood glucose, BMI, and blood pressure. However, their main focus was on the "carotid artery intima-media thickness," which measures subclinical atherosclerosis and is a strong predictor of future heart disease and stroke for women.
Their results showed that women who breastfed for longer had less plaque in their carotid arteries. The authors used sophisticated statistical models to show a significant graded association between the two measures with longer breastfeeding associated with thinner carotid intima-media thickness. The authors examined potential confounders including pre pregnancy BMI, pre pregnancy cholesterol, pre pregnancy blood pressure, pre pregnancy insulin resistance, parity, education, age, number of births since the baseline exam, race, smoking, and time since last birth. These factors were not associated with the primary outcome. When the authors adjusted for pre pregnancy cardiovascular risk factors and smoking, the association between longer breastfeeding and less carotid intima-media thickness remained significant. The authors estimate that suboptimal breastfeeding corresponds to 3 to 5 additional years of aging to the vessels.
This impressive study gives us just one more reason to support mothers in their breastfeeding efforts. We already knew that breastfeeding was linked to lower cardiovascular risk, but now we have additional evidence along the causal pathway for how breastfeeding can lower the risk of heart attacks and strokes.