Risk Stratification in Women with Gestational Diabetes According to and Beyond Current WHO Criteria

The pregnancy outcomes in women with gestational diabetes mellitus (GDM) and 'overt diabetes in pregnancy' were compared and the need for further subclassification was investigated with respect to postpartum outcome risk. Data from 944 women who had been uniformly diagnosed as having GDM in Munich, Germany, between 1998 and 2010, were re-classified into GDM and 'overt diabetes in pregnancy'. Pregnancy related outcomes in the offspring were derived from Bavarian birth registry data. Classification and regression trees were used to identify further GDM sub-phenotypes. In total, 88 women (9.3%) were re-classified as having 'overt diabetes in pregnancy'. Compared to women with GDM, women with 'overt diabetes in pregnancy' used insulin more frequently, and were at increased risk for large for gestational age infants [odds ratio 2.50 (95% confidence interval 1.02, 6.13)], preterm delivery [odds ratio 3.28 (1.02, 10.50)], and low APGAR-score at 5 min [odds ratio 12.70 (1.58, 102.2)]. In the 856 women with GDM, classification and regression tree analyses provided further risk stratification in that a combination of fasting glucose>5.3 mmol/l and 1-h glucose>11.1 mmol/l at GDM diagnosis predicted insulin requirement [OR 5.57 (3.75, 8.27) compared to the rest], and maternal body mass index (BMI)≥35 kg/m(2) predicted large for gestational age status. The new differentiation between GDM and 'overt diabetes in pregnancy' is a first step towards refining classification relevant to fetal and maternal postpartum risk. A combination of glucose levels and maternal BMI at diagnosis of GDM may provide further improvement.