Is abnormal 50-g glucose-challenge testing an independent predictor of adverse pregnancy outcome?

To determine whether an abnormal 50-g glucose-challenge test (GCT) is independently associated with adverse pregnancy outcome.

A retrospective study of women with abnormal GCT (>140 mg/dL) but normal subsequent 100-g oral glucose-tolerance test (OGTT). Pregnancy outcome was compared with that of women with normal GCT (<140 mg/dL).

Of the 79,153 women delivered during the study period, the results of the GCT were available for 14,268. Of these, 809 (5.7%) had an abnormal GCT and normal OGTT and were eligible for the study group. An abnormal GCT was independently associated with an increased risk for macrosomia (odds ratio [OR] = 2.0, 95% CI: 1.5-2.7), large for gestational age (OR = 1.6, 95% CI: 1.3-2.0), cesarean section (OR = 1.3, 95% CI: 1.1-1.6), respiratory morbidity (OR = 1.6, 95% CI: 1.1-2.7) and neonatal hypoglycemia (OR = 1.8, 95% CI: 1.1-3.2). In contrast, an abnormal GCT was associated with decreased risk for preterm delivery at less than 37 weeks (OR = 0.7, 95% CI: 0.5-0.9) and 34 weeks (OR = 0.3, 95% CI: 0.1-0.6). The association between abnormal GCT and adverse pregnancy outcome was unrelated to the degree of GCT abnormality except for cases in which the GCT was extremely high (≥180 mg/dL).

Women with abnormal-GCT result are at increased risk for adverse pregnancy outcome even in the presence of a normal subsequent OGTT.