The BLIiNG study - Breastfeeding length and intensity in gestational diabetes and metabolic effects in a subsequent pregnancy: A cohort study

Background: Gestational diabetes mellitus is associated with higher risk for developing type 2 diabetes. Breastfeeding is protective against the development of type 2 diabetes after gestational diabetes. There are no data regarding the effect of breastfeeding on the development of recurrent gestational diabetes.

Objective: Investigate the relationship of previous breastfeeding duration and intensity with the recurrence of gestational diabetes, and second pregnancy glucose tolerance test results.

Methods: We conducted a questionnaire-based pilot cohort study, enrolling 210 women during a subsequent second pregnancy, after a gestational diabetes-affected first pregnancy. Models for length and intensity of breastfeeding as predictors of the oral glucose tolerance test and for diagnosis of gestational diabetes in second pregnancy were fitted and then adjusted for possible confounders.

Results: Recurrent gestational diabetes rate in the study cohort was 70% (n = 146). In a fully adjusted model high intensity breastfeeding was associated with a lower 2-hour glucose level on the oral glucose tolerance test (by 0.66 mmol/L, 95% CI [0.15-1.17]; p = 0.01) and breastfeeding greater than six months with a lower 1-hour glucose on the oral glucose tolerance test (by 0.67 mmol/L, 95% CI [0.16-1.19]; p = 0.01), compared to women who breastfed less intensively or for a shorter duration respectively. There was an 18% reduction in the risk of gestational diabetes if a woman breastfed for more than six months (RR 0.82, 95% CI [0.69-0.98]; p = 0.03). The association was attenuated in the fully adjusted model (RR 0.89, 95% CI [0.78-1.02]; p = 0.09).

Conclusions and implications for practice: We found the risk of recurrent gestational diabetes was reduced by both increased duration and intensity of breastfeeding. Antenatal lactation education should be embedded into care pathways for women diagnosed with gestational diabetes.