Comparison of efficacy of one-step versus two-step oral glucose tolerance test in pregnant women and its impact on obstetrical outcomes.

Abstract

Objective: To compare the effectiveness of the one-step and two-step OGTT in diagnosing GDM among high-risk pregnant women and to evaluate the impact of each screening strategy on obstetrical outcomes. Study Design: Prospective Comparative Cohort study. Setting: Department of Obstetrics and Gynecology, Dr. Faisal Masood Teaching Hospital, Sargodha, Pakistan. Period: May 2025 to October 2025. Methods: One hundred and ten high-risk pregnant women at 24–28 weeks of gestation were enrolled using non-probability consecutive sampling and allocated equally to Group A (one-step 75 g 2-hour OGTT) and Group B (two-step 50 g GCT followed by 100 g OGTT if indicated) after approval from institutional ethical review committee (number smc/prin/5754 dated 17-4-2025). Primary outcome was GDM diagnosis rate; secondary outcomes included gestational age at delivery, birth weight, neonatal glucose, and maternal and neonatal complications. Results: The mean age of participants was 27.23±4.33 years, with a mean gestational age of 26.91±3.86 weeks. GDM was diagnosed in 30 (54.5%) women in Group A compared with 18 (32.7%) in Group B (p=0.021). Women screened by the one-step approach had significantly higher gestational age at delivery (38.00±1.42 vs. 37.40±1.56 weeks; p=0.038) and higher neonatal blood glucose levels (71.02±14.84 vs. 53.18±20.67 mg/dL; p<0.001). Rates of preterm birth, operative delivery, shoulder dystocia, and polyhydramnios were significantly lower in Group A (p<0.05). No significant differences were observed between the groups regarding large-for-gestational-age infants, perineal injury, postpartum hemorrhage, respiratory distress, neonatal intensive care unit admission, or neonatal hypoglycemia. Conclusion: The one-step OGTT demonstrates higher diagnostic yield in diagnosing GDM and is associated with improved key obstetrical outcomes including lower rates of preterm birth, operative delivery, shoulder dystocia, and polyhydramnios. These findings support the use of the one-step OGTT as an effective screening strategy for high-risk pregnancies.