Background: Adverse pregnancy outcomes associated with gestational diabetes (GDM) are improved by screening & intervention after 24 weeks’ gestation1-3, however there is limited evidence for the benefit of screening & intervention prior to this. The current Australasian Diabetes in Pregnancy Society (ADIPS) guidelines4 therefore do not recommend early universal screening, despite the significant prevalence of GDM diagnosed in the first trimester. Here we present a cohort diagnosed with GDM prior to 24 weeks’ gestation who receive early intensive intervention that we hypothesise attenuates their risk of adverse pregnancy outcomes.
Aim: Determine whether pregnancy outcomes differ amongst women diagnosed with GDM before & after 24 weeks’ gestation in a treated cohort.
Methods: The pregnancy outcomes of 4694 women in our Antenatal Diabetes database between 1991-2011 were reviewed & stratified by timing of GDM diagnosis (<12, 12-23 & ≥24 weeks’ gestation).
Results: From a total of 4694 women with GDM, the majority (n=3331 or 71.0%) were diagnosed ≥24 weeks’ gestation. Amongst women diagnosed < 24 weeks’ gestation (n=1343), 4.5% (n=60) were diagnosed <12 weeks’ gestation & 95.5% (n=1283) were diagnosed between 12-23 weeks’ gestation. Early GDM diagnosis was associated with an increased risk of pre-term delivery (<37 weeks’ gestation) (15.1%, 11.0% & 6.3% for <12, 12-23 & ≥24 weeks’ gestation respectively, X2=31.8, p<0.0001), macrosomia (19.2%, 8.6% & 9.9% for <12, 12-23 & ≥24 weeks’ gestation respectively, X2=7.8, p=0.02), stillbirth (3.9%, 0.7% & 0.3% for <12, 12-23 & ≥24 weeks’ gestation respectively, p=0.03) & neonatal hyperbilirubinaemia (24.0%, 24.7% & 19.5% for <12, 12-23 & ≥24 weeks’ gestation respectively, p=0.0007).
Conclusion: Early GDM diagnosis, particularly in the first trimester, is associated with greater likelihood of adverse neonatal outcomes despite early intensive treatment. Whether this is due to a more severe GDM phenotype and/or suboptimal glycaemic control during pregnancy in this cohort is uncertain; however these pregnancies should be characterized as high risk & require intensive monitoring.