Among women who had gestational diabetes, higher intensity and longer duration of lactation were associated with lower risk of developing type 2 diabetes in the following 2 years, a recent study found.
The study was published by Annals of Internal Medicine on Nov. 24.
The prospective cohort study followed 959 women without diabetes at baseline who had gestational diabetes and delivered a baby at 35 weeks' gestation or later. After 2 years of follow-up, 11.8% had developed diabetes, and there was a significant inverse association between lactation intensity and diabetes risk. Women who breastfed exclusively had a hazard ratio for diabetes of 0.46 compared to women who used formula exclusively, and those who mixed the methods or used mostly formula had hazard ratios of 0.54 and 0.64, respectively, compared to the formula-only group (P for trend=0.016).
The duration of breastfeeding followed a similar trend: Lactation for longer than 10 months had an adjusted hazard ratio for diabetes of 0.43 compared to 0 to 2 months. The ratios were 0.55 for 2 to 5 months and 0.50 for 5 to 10 months (again, compared to 0 to 2 months). Postpartum weight change did slightly attenuate the ratios, but the findings were still significant enough to indicate that the protective association may involve mechanisms other than weight loss, the authors said. Possible explanations include preservation of pancreatic beta cells, reduced inflammation, and improved endothelial function, they speculated.
The study was limited by its 2-year follow-up but benefited from its diverse patient population, the authors also said. Seventy-five percent of the patients were Hispanic, black, or Asian, and 25% had incomes near or below the poverty line. The results suggest that diabetes prevention strategies for postpartum women should initially prioritize optimal lactation intensity and duration, with later implementation of dietary and physical activity modifications, the authors said.