The International Association of Diabetes and Pregnancy Study Groups (IADPSG) recommendsauniversalone-stepscreening strategy with the 75-g oral glucose tolerance test (OGTT) for gestational diabetes mellitus (GDM)(1). Since the adoption of the IADPSG recommendation by the World Health Organization (WHO), the IADPSG criteria are commonly referred to as the 2013 WHO criteria (2). The IADPSG recommendation remains controversialduetothesignificantincrease in GDM prevalence, increased workload, the need for a fasting test, and the risk for increased medicalization of care (3). Several professional associations therefore still recommend a universal two-step screening strategy, using a nonfasting 50-g glucose challenge test (GCT) to determine whether an OGTT should be performed (3). The GCT is easier to perform and is generally bettertoleratedthananOGTT. Inaddition, a two-step screening strategy with a GCT could limit the number of OGTTs. The GCT has been used in combination with the 100-g OGTT or the 75-g OGTT with various diagnostic criteria, but data are lacking on the sensitivity and specificity of the GCT in conjunction with the 2013 WHO criteria for GDM.

We performed a multicentric prospective cohort study, the Belgian Diabetes in Pregnancy Study (BEDIP-N), between 2014 and2017, enrolling2, 006womenbetween 6 and 14 weeks of pregnancy (4). Participants without prediabetes or diabetes in early pregnancy (defined by the American Diabetes Association criteria) received both a GCT and 75-g OGTT between 24 and 28 weeksofpregnancy. Participantsandhealth care providers were blinded for the result of the GCT (4). The GCTs were analyzed centrally at the laboratory of the university hospital of Leuven. Because the GCT