Timing of Gestational Diabetes Diagnosis by Maternal Obesity Status: Impact on Gestational Weight Gain in a Diverse Population.

Background: We hypothesized that earlier gestational diabetes mellitus (GDM) diagnosis and treatment of high-risk women would reduce gestational weight gain (GWG) in the first trimester and overall. Materials and Methods: We evaluated timing of GDM diagnosis among 5,391 pregnant women who delivered singleton births 2010-2013 in a large diverse health maintenance organization (HMO). All GDM screening was by the same oral glucose tolerance testing protocol; GDM treatment protocols were also consistent irrespective of timing of diagnosis. Women without risk factors were universally screened at 24-28 weeks gestation (Usual). Early screening was recommended in obese and other high-risk women at the first prenatal visit; those who screened negative Early were rescreened at 24-28 weeks (Early+Usual). Results: Average GWG for all women was 12.8 kg; 10.7% of women were diagnosed with GDM. Average GWG for all women diagnosed with GDM was 10.7 kg, adjusted for gestational age. Women with EarlyGDM averaged 2.4 kg less GWG than women diagnosed with UsualGDM (p < 0.0001). Among obese women, only women diagnosed with EarlyGDM averaged overall GWG within Institute of Medicine (IOM) weight guidelines (mean 8.1 kg) and were weight neutral in the first trimester (-0.2 kg). Overall, 43% of all pregnant women exceeded IOM GWG guidelines (gained more total weight than recommended); 60% of obese women exceeded guidelines. Obese women diagnosed with GDM were less likely to exceed IOM guidelines if diagnosed earlier in pregnancy (35% EarlyGDM vs. 59% UsualGDM exceeded guidelines, p < 0.0001). Conclusion: Our results suggest that EarlyGDM diagnosis (and thus treatment) in high-risk women is beneficial for optimizing GWG.