Neonatal outcomes among offspring of obese women diagnosed with gestational diabetes mellitus in early versus late pregnancy.

Background: Maternal metabolic derangements associated with early pregnancy gestational diabetes may affect the fetus differently compared with gestational diabetes diagnosed later in pregnancy. The aim of this observational study was to assess neonatal outcomes according to timing of gestational diabetes diagnosis in obese women.

Methods: Women ≥18 years of age with a pre-pregnancy body mass index ≥30 kg/m2 were grouped according to the results of a 75 g 2-h oral glucose tolerance test performed at 13.1 weeks of gestation and repeated at 23.4 weeks if normal at first testing. The main outcomes were birthweight and large for gestational age.

Results: Out of 361 women, 164 (45.4%) were diagnosed with gestational diabetes, 133 (81.1%) of them in early pregnancy. The mean offspring birthweight was 3673 g (standard deviation (SD) 589 g) in the early and 3710 g (SD 552 g) in the late gestational diabetes group. In a multivariate logit model, the odds ratio for large for gestational age was 2.01 (95% CI: 0.39-10.39) in early compared with late gestational diabetes.

Conclusions: We observed no statistically significant differences in neonatal outcomes according to timing of gestational diabetes diagnosis. In addition to lack of power, early treatment of hyperglycemia may partly explain the results.