Objectives: To assess the risk factors that predict the development of pregnancy induced hypertension (PIH) among gestational diabetes mellitus (GDM) patients in the Australian Capital Territory (ACT) and to compare the perinatal outcomes of women with GDM-only (GO) to women with GDM superimposed with PIH (GP).
Research Design and Methods: A retrospective clinical audit of GDM patients treated in the ACT between 01/01/2010 and 30/06/2014 was conducted. Maternal demographic data and neonatal/maternal clinical outcomes data were analysed.
Results: GP (n=85) compared to GO (n= 890) GDM mothers were more obese (body mass index [BMI] 33.4±9.3 vs 27.2±6.8 kg/m2, p<0.001), more likely to be diagnosed with GDM earlier (26.5±4.5 vs 27.6±3.7 weeks, p=0.041), had a higher oral glucose tolerance test (OGTT) fasting glucose level (5.7±0.7 vs 5.3±1.0 mmol/l, p<0.001), a higher HbA1c level (5.6±0.4% vs 5.4±0.5%, p=0.013), and a lower Vitamin D level (48.1±20.5 vs 58.7±21 nmol/L, p=0.005). On stepwise regression analysis, only higher BMI (odds ratio 1.050, 95% confidence interval 1.001-1.101) and higher OGTT fasting glucose level (odds ratio 2.013, 95% confidence interval 1.200-3.374) increased the risk of having PIH among GDM patients. Regarding the perinatal outcomes, GP patients had more caesarean-sections (51.8% vs 33.5%, p<0.001), more preterm delivery (before 37 weeks) (20% vs 6.9%, p<0.001) and were more likely to require insulin treatment (55.3% vs 38.8%, p=0.004). Babies of GP had higher rates of hypoglycaemia (17.6% vs 6.1%, p<0.001), higher rates of respiratory distress (12.9% vs 5.6%, p= 0.016), and higher rates of neonatal special care admission (25.9% vs 12.8%, p=0.003).
Conclusion: GDM patients who have higher BMI and higher OGTT fasting glucose levels are more likely to develop PIH. GDM patients with PIH have worse perinatal outcomes.