The association between glucose challenge test, obesity and pregnancy outcome in 6390 non-diabetic women

Objective: To evaluate the association between obesity, glucose challenge test (GCT) and pregnancy outcome. Methods: A prospective cohort study of 6854 consecutive gravid patients screened for gestational diabetes (GDM) using 50-gram GCT, at 24-28 weeks' gestation was performed. A screening value 130 mg/dl was followed by 100 gr oral GTT. Patients who were diagnosed with GDM were excluded. For purpose of analysis patients were categorized by prepregnancy BMI and by different GCT thresholds. Maternal outcome was defined by rate of preeclampsia, gestational age at delivery, cesarean section (CS) rate and the need for labor induction. Neonatal outcome was defined by fetal size (macrosomia/LGA), arterial cord pH, respiratory complications and neonatal intensive care unit (NICU) admission. Results: Overall, a positive GCT result (GCT 130 mg/dl) was identified in 2541/6854 (37%) women. GDM was further diagnosed in 464/6854 (6.8%) of subjects. In both groups of screening results ( > 130 mg/dl and < 130 mg/dl), the obese women were significantly older, gained more weight during pregnancy and had a lower rate of nulliparity in comparison to the non obese women. The obese women had higher rates of macrosomia, LGA and induction of labor. No difference was found in mean birth weight, the total rate of cesarean section, preterm delivery, 5 minute Apgar score 7, mean arterial cord pH, NICU admission and a need for respiratory support in comparison to non obese women in both groups of screening results. A gradual increase in the rate of macrosomia, LGA and cesarean section was identified in both obese and non-obese women in relation to increasing GCT severity categories. Conclusion: Fetal size and cesarean section rate are associated with the degree of carbohydrate intolerance (screening results). Furthermore, obesity remains the main contributor impacting fetal size.