Perinatal Outcomes in Early and Late Gestational Diabetes Mellitus After Treatment from 24-28 weeks’ Gestation: A TOBOGM Secondary Analysis

Objective Most gestational diabetes mellitus (GDM) studies have combined women whether or not hyperglycemia was present earlier in pregnancy. This study compared perinatal outcomes between women with early GDM (EGDM: diagnosed <20 weeks’, but untreated until 24-28 weeks’ if GDM still present), late GDM (LGDM: present only at 24-28 weeks’), and normoglycemia at 24-28 weeks’ (controls). Research Design and Methods This is a secondary analysis of a randomized controlled treatment trial of early GDM (defined using WHO 2013 criteria) among women with risk factors <20 weeks’ gestation. Those receiving early GDM treatment were excluded. GDM was treated if present at 24-28 weeks’. The primary outcome was a composite of birth <37+0 weeks’, birthweight≥4500g, birth trauma, neonatal respiratory distress, phototherapy, stillbirth/neonatal death and/or shoulder dystocia. Comparisons were adjusted for age, ethnicity, body mass index (BMI), site, smoking, primigravity and education. Results Women with EGDM (n=254) and LGDM (n=467) had shorter pregnancy duration than controls (n=2339). BMI was lowest with LGDM. The composite was increased with EGDM (OR 1.59, 95%CI 1.18-2.12)) but not LGDM (OR 1.19, 95%CI 0.94-1.50)). Induction of labor was higher in both GDM groups. EGDM (but not LGDM) had higher birth centile, preterm birth rate and neonatal jaundice compared to controls. The greatest need for insulin and/or metformin was with EGDM. Conclusions Adverse perinatal outcomes were increased with EGDM despite treatment from 24-28 weeks’, suggesting the need to initiate treatment early, and more aggressively, to reduce the effects of exposure to the more severe maternal hyperglycemia from early pregnancy.