Reduced risk of heart disease for mothers who breastfeed

According to a new study by researchers from the American College of Cardiology, women who have normal blood pressure while pregnant and breastfeed their babies for a minimum of 6 months after birth have a reduced risk of heart disease in later life.

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In the study, women who had breastfed for a minimum of 6 months exhibited better markers of cardiovascular health in later life, compared to women who didn’t breastfeed. It is important to note that the findings were not observed for women who had high blood pressure during pregnancy.

Many studies have associated breastfeeding with short-term health benefits, whilst only a few studies have focussed on the impact of breastfeeding on later life, this novel research was the first to detail the effect of breastfeeding on markers of heart health in younger and middle-aged women, around ten years after childbirth.

The findings have reinforced the theory that breastfeeding during pregnancy in women with normal pressure is beneficial, however, the finding that the same benefits are not observed in in women with high blood pressure during pregnancy is a first.

The study adds to the evidence that lactation is important not just for the baby but for the mother. Breastfeeding seems to be cardioprotective in these women, as evidenced by improved cholesterol and markers of subclinical cardiovascular disease."

Dr. Malamo Countouris, Lead Author & Cardiology Fellow at The University of Pittsburgh

Between 1998 and 2004, the study enrolled 678 pregnant women from over 52 clinics across Michigan, USA. In the 7-15 years following the study (an average of just over 11 years for each woman), participants underwent a health assessment.

They were asked to state the period of time they breastfed following each pregnancy, and researchers then measured their cholesterol, triglyceride levels, blood pressure and the diameter and thickness of the carotid artery. All of these are factors often used to determine heart disease risk and give an early indication of possible issues in patients who do not suffer from heart disease at the time.

The women were split into three groups: those who breastfed for 6 months or more for each pregnancy (133), those who breastfed for less than six months for each pregnancy (284), and those who had never breastfed (157).

Women with normal blood pressure while pregnant and those with high blood pressure while pregnant were separately assessed. Those who breastfed for longer were typically older, held a higher socio-economic status and had a lower body mass index (BMI).

Once the researchers modified the results for these and other influential factors, it was found that those with normal blood pressure during pregnancy who breastfed for six or more months had markedly higher levels of high density lipoproteins (HDL, or “good” cholesterol), healthier carotid artery thickness and lower triglyceride levels compared to the participants who had never breastfed.

The outcomes suggest that a woman’s risk of heart disease may be reduced if they breastfeed for a minimum of six months for each pregnancy.

Dr. Countouris, the lead author of the study, suggested that the results may be due to expression of the hormone oxytocin, which has been shown to increase during breastfeeding, and lower blood pressure. He also pointed to another study, which discovered that lactating could offset some metabolic changes that take place during pregnancy.

There's a lot we still don't understand about the accumulation of cardiovascular risks in women. 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."

Dr. Malamo Countouris, Lead Author & Cardiology Fellow at The University of Pittsburgh

Women with high blood pressure during pregnancy were found to receive no cardiovasucular benefits, but Countouris added that there may have been too few women with high blood pressure during pregnancy enrolled in the study to uncover any possible cardiovascular benefits in this group.

Another factor that may have affected the results was the reliance on participants reporting information regarding high blood pressure or preeclampsia (a disorder in pregnant women characterized by high blood pressure and proteinuria, which is known to increase the risk of heart disease) that was diagnosed in subsequent pregnancies.

Researchers concluded that future amendments could include tracking women for a greater period of time, or enrolling more participants.