The relationship between previous breastfeeding duration and intensity with recurrent gestational diabetes
There were 117 (56%) women who breastfed >6 months and of these 73 (63%) developed GDM in their second subsequent pregnancy. There was an 18% reduction in the risk of recurrent GDM for any amount of breastfeeding greater than six months after the first GDM pregnancy (74/117 (63%) vs. 71/92 (77%), RR 0.82, 95% CI 0.69–0.98, P = 0.03) (Table 3). Length of breastfeeding greater than six months remained a significant predictor for reduced GDM diagnosis when adjusted for age (RR 0.79, CI 95% 0.67–0.94, P = 0.01) or BMI (RR 0.84, CI 95% 0.70–1.00, P = 0.05). After adjusting for both age and BMI there remained a 19% reduction in the risk of GDM if a woman breastfed for more than six months (RR 0.81, 95% CI 0.68–0.96,P = 0.01). The association was attenuated in the fully adjusted model with the following confounders, medical treatment of GDM in the first pregnancy, BMI, maternal age and ethnicity (RR 0.89, 95% CI 0.78–1.02, P = 0.09) (Table 3).
Women who breastfed in the high intensity range (≥19 BLISS; 63%) had a 17% reduction in the risk of being diagnosed with GDM compared to lower intensity breastfeeding groups, (<19 BLISS, 71/112 (63%) vs. 75/98 (77%), P = 0.04) (Table 3). In the adjusted model that included age and BMI, the association was stronger, with a 22% reduction in GDM (RR 0.78, 95% CI 0.63–0.96, P = 0.02). However, in the fully adjusted model, the association between BLISS score groups and GDM diagnosis was attenuated (RR 0.90, 95% CI 0.77–1.05, P = 0.17) (Table 3).