To compare the short-term perinatal outcomes of the International Association of Diabetes and Pregnancy Study Groups (IADPSG) and Carpenter-Coustan screening methods for prenatal diabetes mellitus was the goal of the study. Participants in this single-site, blinded, randomised, comparative efficacy study received a nonfasting 50-g oral glucose tolerance test and were randomised to additional screening using either IADPSG or Carpenter-Coustan criteria if their results were less than 200 mg/dL. Gestational diabetes was treated as part of normal clinical care. The incidence of large-for-gestational-age (LGA) newborns was the primary endpoint. Secondary outcomes that had been predetermined included small-for-gestational-age (SGA) neonates, caesarean delivery, and neonatal and mother composites of poor perinatal outcomes. Assuming a 15% incidence of LGA neonates in the Carpenter-Coustan group, 782 individuals gave more than 80% power to detect a 7% absolute risk decrease with IADPSG usage; intended enrollment was 920 to account for expected attrition. From June 2015 through February 2019, 1,016 people were registered, with 921 assigned to the IADPSG or Carpenter-Coustan groups. The IADPSG group had a higher prevalence of gestational diabetes and used more diabetic medications; there were no differences in LGA newborns overall or among mothers without gestational diabetes. Those that were tested with IADPSG had greater neonatal morbidity rates but fewer study-related adverse events. The rates of SGA newborns, caesarean delivery, and the composite of mother morbidity did not change substantially across study groups.

The IADPSG screening criteria resulted in more women being identified and treated for gestational diabetes than Carpenter-Coustan, without a reduction in LGA birth weight or maternal or neonatal morbidity.