The Association Between Breastfeeding and Risk of Cardiovascular Disease Among Women with a History of Type 2 Diabetes or Gestational Diabetes
by Anne Eglash MD, IBCLC, FABM
Diabetes is a major risk factor for cardiovascular diseases, including stroke and heart attack. Medical management of diabetes focuses on ways to prevent these cardiovascular risks, since these are the major reasons for hospitalization and death among people with type 2 diabetes. In addition, people with gestational diabetes have a higher future risk of cardiovascular disease, even if they do not develop type 2 diabetes.
The study for this week analyzed data from two large US nurse cohorts to evaluate the association between breastfeeding and cardiovascular disease risk in women with type 2 diabetes and gestational diabetes. Controlling for BMI, parity, socioeconomic status, education, smoking history and other potential confounders, the researchers found that women with type 2 diabetes who cumulatively breastfed for over 18 months had a 38% lower risk of coronary heart disease compared to women who did not breastfeed. Similarly, women with a history of gestational diabetes who did not progress to type 2 diabetes and breastfed for over 18 months had a 62% lower coronary heart disease risk.
The findings provide evidence that extended breastfeeding for over 18 months may have protective cardiovascular benefits for women with both type 2 and gestational diabetes, independent of other cardiovascular risk factors.
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- The greater the number of cumulative months of breastfeeding, the greater the protection from heart disease.
- The greater the number of cumulative months of breastfeeding, the lower the risk of stroke.
- Among women with a history of gestational diabetes, the number of months of exclusive breastfeeding was more protective from heart disease as compared to any breastfeeding.
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Abstract
Objective
Breastfeeding duration is inversely associated with risks of cardiovascular disease (CVD) and type 2 diabetes in parous women. However, the association among women at high risk, including women with type 2 diabetes or gestational diabetes (GDM) is unclear.
Research Design and Methods
We included 15,146 parous women with type 2 diabetes from the Nurses’ Health Study I and II (NHS, NHS II) and 4,537 women with a history of GDM from NHS II. Participants reported history of breastfeeding via follow-up questionnaires. Incident CVD by 2017 comprised stroke or coronary heart disease (CHD: myocardial infarction, coronary revascularization). Adjusted hazard ratios (aHRs) and 95% CIs were estimated using Cox models.
Results
We documented 1,159 incident CVD cases among women with type 2 diabetes in both cohorts during 188,874 person-years of follow-up and 132 incident CVD cases among women with a GDM history during 100,218 person-years of follow-up. Longer lifetime duration of breastfeeding was significantly associated with lower CVD risk among women with type 2 diabetes, pooled aHR of 0.68 (95% CI 0.54–0.85) for >18 months versus 0 months, and 0.94 (0.91–0.98) per 6-month increment in breastfeeding. Similar associations were observed with CHD (pooled aHR 0.93 [0.88–0.97]), however, not with stroke (0.96 [0.91–1.02]) per 6-month increment in breastfeeding. Among women with GDM history, >18 months versus 0 months of breastfeeding was associated with an aHR of 0.49 (0.28–0.86) for total CVD.
Conclusions
Longer duration of breastfeeding was associated with lower risk of CVD in women with type 2 diabetes or GDM.
The researchers found that breastfeeding duration or exclusive breastfeeding was not associated with risk of stroke.
Previous studies demonstrating lower heart disease risk with longer breastfeeding have been criticized based on the possibility that women who breastfeed longer are less likely to have diseases that increase their risk of heart disease, particularly as diabetes.
This study refutes that concern, as this data shows how women with type 2 diabetes are less likely to have heart disease if they breastfeed, with longer and exclusive breastfeeding being more protective.
Gestational diabetes affects 5-10% of pregnant women in the USA, and I didn’t realize that these individuals have a higher risk of heart disease even if they never are diagnosed with type 2 diabetes. This study demonstrates strong protection of cardiovascular disease in this population by breastfeeding.
The authors propose possible biologic mechanisms to explain these findings. There is evidence that breastfeeding improves insulin secretion by increasing the number and function of insulin-secreting cells in the pancreas (β cells). Breastfeeding also mobilizes stored fat and re-establishes pre-pregnancy blood sugar metabolism, thereby reversing some of the negative metabolic consequences of pregnancy.
This evidence strongly supports encouraging breastfeeding for parental cardiovascular benefits, especially for lactating individuals with gestational or type 2 diabetes.