Third trimester re-screening for gestational diabetes in morbidly obese women despite earlier negative test can reveal risks for obstetrical complications.

Late screening in pregnancy may reveal GDM among women with previous normal glucose screening, particularly among those with late third trimester BMI ≥ 35 kg/m , GDM in a previous pregnancy or fasting glucose >95 mg/dl. Women diagnosed with GDM at >34 weeks following normal glucose screening at 24-28 weeks are at higher risk for adverse perinatal outcomes. For women with morbid obesity, or suspected macrosomia or polyhydramnios in the late third trimester, and normal glucose screening in the second trimester, retesting should be considered.