Comparison of risk factors and pregnancy outcomes of gestational diabetes mellitus diagnosed during early and late pregnancy

Objective: To compare risk factors and pregnancy outcomes of gestational diabetes mellitus (GDM) diagnosed during early and late pregnancy. Design: Prospective population-based cohort study. Setting: Community health care centers of Isfahan, Iran. Participants and measurements: 1000 pregnant women who were eligible and consented to participate underwent fasting plasma glucose testing at the first prenatal visit (6-14 weeks). The women free from GDM or overt diabetes were screened at 24-28 weeks of gestation using a 75-g, 2-hour oral glucose tolerance test. The diagnosis of GDM was reached through the International Association of the Diabetes and Pregnancy Study Groups. Early-onset GDM was defined as the diagnosis of GDM at the first prenatal visit. Late-onset GDM was defined as the diagnosis of GDM later at 24-28 weeks. Findings: Prevalence of GDM was 10% (95% CI: 8.1-11.9) at the first prenatal visit. GDM incidence was 9.3% (95% CI: 7.4-11.2) at 24-28 weeks of gestation. Family history of diabetes, and previous gestational diabetes and maternal age were the independent risk factors for GDM during early and late diagnosis. GDM was associated with increased risk of macrosomia, large for gestational age, and cesarean section in both periods while, neonates of women with early-onset GDM were more likely to have an apgar score at 1-min < 7, and neonatal respiratory distress syndrome and were more admitted to the neonatal intensive care unit. Key conclusion and implication for practice: Despite early screening and current practice management, early-onset GDM was associated with poorer pregnancy outcomes compared to the late-onset group. Women with early-onset GDM would benefit from more strict surveillance and management strategies to improve pregnancy outcomes. Further studies are needed to evaluate the efficacy of alternative management approaches in these high risk women.