The Implications of a "Flat" Oral Glucose Tolerance Test Curve in Pregnancy.

Abstract

To determine whether pregnant women with "flat" oral glucose tolerance test (OGTT) curves are at increased risk of adverse perinatal outcomes. We conducted a retrospective cohort study comparing the perinatal outcomes of pregnant women whose 100g OGTT curve was "flat" (fasting serum glucose below 95 mg/dl and the remaining values below 100 mg/dl) to those of women whose OGTT curve was "normal". Primary outcomes compared were the prevalence of macrosomic and small for gestational age (SGA) neonates. Secondary outcomes included hypertensive disorders of pregnancy (HDP), intrauterine fetal demise, placental abruption, induction of labor, meconium-stained amniotic fluid (MSAF), mode of delivery, postpartum hemorrhage (PPH), blood product transfusion, postpartum readmission, umbilical artery pH <7.1, Apgar score <7 at 5 minutes, neonatal intensive care unit (NICU) admission, neonatal respiratory and infectious morbidity, and hypoglycemia. Composite adverse maternal and neonatal outcomes were also evaluated. There were 1,060 patients in the study group and 10,591 patients in the control group. Patients with a flat OGTT had a reduced risk of delivering a macrosomic neonate (11.4% vs. 15.1% OR 0.7 [0.58-0.89] p=0.001) and having an unplanned cesarean delivery (7.5% vs 10.2% OR 0.8 [0.58-0.96] p=0.002). There was no difference in the rate of composite adverse maternal (14.0% vs 15.4% OR 0.9 [0.7-1.0] p=0.1) or neonatal outcome (5.3% vs. 4.5% OR 1.2 [0.9-1.5] p=0.15). Neonates had a slightly lower mean birthweight (3474g vs. 3505g, p=0.04), but the rate of SGA was similar in the two groups (2.5% vs.1.8% OR 1.3[0.9-2.0] p=0.08). Conclusions Pregnant women whose OGTT curve is flat have a lower risk of delivering macrosomic neonates and undergoing unplanned cesarean delivery and are not at increased risk of adverse maternal or neonatal outcomes. More research is required to evaluate the relationship between different OGTT curves and th.