Abnormal glucose screening tests in pregnancy: a risk factor for fetal macrosomia.

Of 2276 patients who underwent screening for gestational diabetes mellitus, 1854 (81.5%) had normal glucose screening tests after a 50-g carbohydrate load (serum glucose below 135 mg/dL). Three hundred fifty-seven patients (15.7%) had abnormal glucose screening tests and went on to complete three-hour glucose tolerance tests, of whom 176 (48.7%) were shown to be nondiabetic when further tested using a carbohydrate-loaded, 100-g glucose, three-hour glucose tolerance test. The 176 women with abnormal glucose screens but normal glucose tolerance tests were compared with the 1854 who had normal screening values. The frequency of infants weighing more than 4000 g (greater than 95th percentile at our institution) was 11.9% in the study group and 6.4% in the control group (P = .0086). When the data were corrected for other macrosomia risk factors (advanced age, high parity, obesity, white race, and prolonged gestation), there was still a significantly higher frequency of macrosomia in the study group; this fact suggests that patients with minor abnormalities of carbohydrate metabolism during pregnancy are at risk for delivering a macrosomic infant.