Contribution of gestational diabetes mellitus heterogeneity and prepregnancy body mass index to large-for-gestational-age infants-A retrospective case-control study

Objective To study the associations between heterogeneity of gestational diabetes mellitus (GDM) subtype/prepregnancy body mass index (pre-BMI) and large-for-gestational-age (LGA) infants of Chinese women. Methods We performed a retrospective case-control study of 299 women with GDM and 204 women with normal glucose tolerance (NGT), using oral glucose tolerance test-based indices performed at 24-25 weeks of gestation. Women with GDM were classified into the following three physiologic subtypes: GDM with a predominant insulin-secretion defect (GDM-dysfunction), GDM with a predominant insulin-sensitivity defect (GDM-resistance), or GDM with both defects (GDM-mixed). We then used a binary logistic regression model to evaluate the potential associations of GDM subtypes and pre-BMI with newborn macrosomia or LGA. Results Women with GDM-resistance had a higher pre-BMI (P < 0.001), whereas women in the GDM-dysfunction and GDM-mixed groups had pre-BMIs comparable to the NGT group. In the logistic regression model, women in the GDM-mixed group exhibited an increased risk of bearing newborns with macrosomia and LGA, and women in the GDM-dysfunction group tended to have newborns with LGA after adjusting for pre-BMI and other potential confounders. Women who were overweight or obese prepregnancy manifested an increased risk of having newborns with macrosomia and LGA relative to normal-weight women, regardless of whether values were unadjusted or adjusted for all potential confounders. There was no significant interaction between GDM subtype and pre-BMI for any of the studied outcomes. Conclusions Heterogeneity of GDM (GDM-dysfunction and GDM-mixed) and prepregnancy overweight/obesity were independently associated with LGA in Chinese women. There was no significant interaction between GDM subtypes and pre-BMI for LGA.