The BLIiNG study - Breastfeeding length and intensity in gestational
diabetes and metabolic effects in a subsequent pregnancy: a cohort study
Abstract
Objective To investigate if increased length and intensity of
breastfeeding mediates gestational diabetes mellitus (GDM) risk in a
subsequent pregnancy. Design Multisite cohort study. Setting Western
Sydney, Australia, March 2017–April 2019. Population Women with a
second subsequent pregnancy after a GDM-affected first pregnancy.
Methods Information on breastfeeding experience, intensity and GDM
management in the first pregnancy was collected by questionnaire. The
results of the oral glucose tolerance test (OGTT) in the second
pregnancy were also recorded. Multivariable models for OGTT and for
diagnosis of GDM were fitted and then adjusted for medical treatment of
GDM in the first pregnancy, BMI, age at current pregnancy and ethnicity.
Main outcome measures Second pregnancy oral glucose tolerance test
(OGTT) blood glucose results and diagnosis of GDM. Results We recruited
227 women with 210 eligible for analysis. Of these women, 146 (70%)
were diagnosed with recurrent GDM. We found a 19% reduction in the risk
of GDM in a subsequent pregnancy if a woman breastfed for more than six
months (RR 0.81, 95% CI 0.68–0.96) after adjusting for both age and
BMI. In a fully adjusted model, the association was attenuated (RR 0.89,
95% CI 0.78–1.02). With the same adjusted confounders, however, both
high intensity breastfeeding (2 h OGTT, P = 0.01) and breastfeeding for
greater than six months (1 h OGTT, P = 0.01) were associated with a mean
blood glucose decrease of 0.7mmol/L. Conclusion We found the risk of
recurrent GDM was reduced by both increased duration and intensity of
breastfeeding.