Recent ADIPS guidelines note that high-risk pregnant women are more likely to have gestational diabetes mellitus (GDM) and therefore, are recommended to be screened earlier (<20 weeks). Women diagnosed with early GDM are at increased risk of adverse outcomes (Immanuel & Simmons, 2017) and are treated once diagnosed including glucose and weight management. This study compared the clinical characteristics, and pregnancy outcomes of women with GDM diagnosed at <20 weeks gestation and those at ≥20 weeks gestation, in a large treated multiethnic cohort.
Data were from a retrospective combined clinical review of GDM women diagnosed by ADIPS 1998 criteria and managed at Liverpool and Bankstown-Lidcombe hospitals from 2010-2016. Women with fasting plasma glucose ≥7.0 mmol/L and/or 2hr plasma glucose ≥11.1 mmol/L, during pregnancy, were excluded. Characteristics were compared using Chi-squared and ANOVA. Odd Ratios (ORs) and 95% confidence intervals (95%CI) were assessed using multivariable logistic regression.
Women diagnosed earlier (n=1,216) were more likely to have high-risk characteristics: (older, higher body mass index, greater proportion with previous GDM and family history of diabetes, and higher HbA1c at diagnosis) than those diagnosed later during pregnancy (n=2,649), (P<0.05). However, fasting and 2hr glucose concentrations were similar. Women with early GDM were most likely to require insulin during pregnancy (OR 1.90; 95%CI: 1.58, 2.29). Women diagnosed earlier also had a higher risk of congenital malformations (OR 1.45; 95%CI: 1.01, 2.08); preterm delivery (OR 1.61; 95%CI: 1.26, 2.08) and neonatal hypoglycaemia (OR 1.60; 95%CI: 1.34, 1.91). The risk of caesarean section was lower in those diagnosed early (OR 0.50; 95%CI: 0.43, 0.58). The risk of small- and large- for gestational age was not statistically different between the two study groups (P>0.05).
Poorer pregnancy outcomes were found among women with early diagnosis of GDM in spite of standard glycaemic management. Additional interventions beyond existing management may be required for women with early GDM.