Pregnancy outcomes in women with an early diagnosis of gestational diabetes mellitus.

Aim: To examine pregnancy outcomes in women with gestational diabetes mellitus (GDM) based on the timing of diagnosis.

Method: We compared demographics, blood sugars and outcomes between women diagnosed before (n = 167) or after 24 weeks' gestation (n = 1202) in a single hospital between 2009 and 2012. Because early screening is risk-based we used propensity score modelling and conditional logistic regression to account for systematic differences.

Results: Women diagnosed with GDM before 24 weeks were more likely to be obese and they were less likely to have excess gestational weight gain (35 vs. 45%, p = 0.04). Early diagnosis was associated with more frequent therapy including glyburide (65 vs. 56%, p < 0.001) and insulin (19 vs 6%, p < 0.001). After propensity score modelling and accounting for covariates, early diagnosis was associated with an increased risk for macrosomia (OR 2, 95% 1-4.15, p = 0.0498). Early diagnosis was not associated with other adverse outcomes. In a subgroup analysis comparing women treated with glyburide prior to 24 weeks compared to those diagnosed after 24 weeks, early diagnosis in women treated with glyburide was associated with an increased risk for macrosomia (OR 2.3, 95% CI 1.1-5.4, P = 0.04).

Conclusion: Women diagnosed with GDM before 24 weeks have unique features, are at risk for adverse outcomes, and require targeted approaches to therapy.