Abstract

Objective: To assess the incidence of gestational diabetes mellitus (GDM) in pregnant women who have tested negative for gestational diabetes during first-trimester screening. Additionally, to identify first-trimester factors that can predict GDM at 24–28 weeks or later in Southern Thailand. Material and Methods: A prospective study was conducted from March 2018 and March 2020 in two tertiary hospitals. A two-step approach for GDM screening was performed at the first trimester (≤14 weeks) and at 24–28 weeks or later. First-trimester factors associated with the development of GDM at 24 weeks or later were analyzed using multivariable logistic regression. Results: Of 408 pregnant women who had no GDM from screening at the first trimester, 43 women (10.5%) were diagnosed with GDM at 24 weeks of gestation or later. One-hour plasma glucose after 50 grams (g) GCT and HbA1c at the first trimester were found to be significantly higher in GDM women than in non-GDM women. Women with a history of hypertensive disorders of pregnancy (HDP) or GDM in a prior pregnancy, subscapular fat thickness >18.8 millimeter, 1-hour plasma glucose after 50g GCT >165 milligrams per deciliter (mg/dL), and HbA1c >5.3% at first trimester had 2-to 4-fold higher odds of developing GDM. Conclusion: Approximately, one of 10 pregnant women having had no GDM at first trimester was diagnosed GDM at 24 weeks or later. Close monitoring for the diagnosis of GDM and early treatment should be systematically planned in women with history of HDP or GDM in a prior pregnancy, high subscapular fat thickness, and 1-hour plasma glucose after 50g GCT or HbA1c at first trimester.