Third trimester abnormal oral glucose tolerance test and adverse perinatal outcome.

OBJECTIVE To compare perinatal outcome of women after third trimester oral glucose tolerance test (GTT) following normal glucose challenge test (GCT) stratified by test results. STUDY DESIGN Retrospective cohort study of women delivered in a tertiary, university affiliated medical center (2007-2012). Inclusion criteria were women with a normal 50 g GCT (<140 mg/dl) followed by GTT, who delivered a live-born fetus >28 gestational weeks. Gestational diabetes mellitus (GDM) was defined as ≥2 pathological values on GTT (Carpenter and Coustan's criteria). Perinatal outcome was stratified by GTT results: normal (if all 4 values were normal), single pathological value or GDM. Logistic regression analysis was utilized to adjust outcomes to potential confounders. RESULTS Overall, 323 women met inclusion criteria. Of them, 277 (85.8%) had 4 normal values, 32 (9.9%) had a single pathological value and 14 (4.3%) had late-onset GDM. Infants of mothers diagnosed and treated as GDM had lower birth weights, compared to non-diabetics and those with a single pathological value GTT. Mothers with GTT ≥1 pathological values had statistically insignificant higher rates of cesarean delivery. However, this difference was not significant after adjustment to potential confounders. CONCLUSION Treatment of late-onset GDM may lead to lower birthweights, presumably due to glucose control. No association was found with cesarean delivery or neonatal outcome.