Obstetric outcomes with a false-positive one-hour glucose challenge test by the Carpenter-Coustan criteria

Pregnancies complicated by a false-positive one-hour glucose challenge test (GCT), as determined by the National Diabetes Data Group (NDDG) criteria, have higher rates of adverse maternal and neonatal outcomes. This study was conducted to determine if pregnancies complicated by a false-positive GCT, as determined by the Carpenter-Coustan (CC) criteria, also have higher rates of adverse maternal and neonatal outcomes.

In this retrospective case-control study, we compared 165 patients with a false-positive GCT, as determined by the Carpenter-Coustan criteria, to a cohort of 165 pregnant controls with a normal screening GCT. Multiple variables for maternal and neonatal outcomes were compared between the two groups.

The racial distribution and gestational age of delivery were similar in both groups. The study group had a higher one-hour GCT (148.2 mg/dl vs. 95.3 mg/dl, p < 0.001), was older (27.4 yrs vs. 23.8 years, p < 0.001), was more likely to be multiparous (71.5% vs. 58.2%, p = 0.011), and had a higher BMI (26.7 kg/m2 vs. 24.6 kg/m2, p = 0.002). There were no differences between the two groups in mode of delivery, birth weight, rates of macrosomia, shoulder dystocia, antenatal death and maternal laceration. There were also no differences between the two groups in rates of preeclampsia, chorioamnionitis, endometritis, ICN admission, neonatal hypoglycemia, Erb's palsy, clavicular fracture, neonatal sepsis, neonatal death or use of phototherapy.

Women with a false-positive one-hour GCT by the Carpenter-Coustan criteria do not have higher rates of adverse perinatal outcomes. Using the Carpenter-Coustan criteria to diagnose GDM appears to be superior to NDDG criteria in terms of avoiding adverse maternal and neonatal outcomes.