Lifetime duration of breastfeeding and cardiovascular risk in women with type 2 diabetes or a history of gestational diabetes: Findings from two large prospective cohorts

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 Nurses’ Health Study I and II (NHS, NHS2) and 4,537 women with a history of GDM from NHS2. 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 [aHR 95% CI] 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 0.68 (95% CI 0.54-0.85) for >18 months vs 0 months and 0.94 (0.91-0.98) per 6 months 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 months increment in breastfeeding). Among women with GDM history, >18 months vs 0 months of breastfeeding was associated with aHR 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.