Risk factors for gestational diabetes mellitus: Implications for the application of screening guidelines

Background: Recent evidence has shown the importance of ensuring that all pregnancies with gestational diabetes mellitus (GDM) are identified and managed appropriately. However, there remains a lack of consensus as to how to best identify these women. Aim: To review risk profiles of women with GDM and to evaluate international GDM screening recommendations. Methods: A retrospective observational study was carried out at a tertiary referral hospital (Monash Medical Centre, Victoria). Data of singleton pregnancies in women (without pre-existing diabetes mellitus) giving birth in 2007 from the Birthing Outcomes System were analysed and the performance of the British National Institute for Health and Clinical Excellence (NICE), the American Diabetes Association (ADA) and the Australasian Diabetes in Pregnancy Society (ADIPS) GDM selective screening guidelines were evaluated. Predictors of GDM were identified with logistic regression, and sensitivity and specificity of international screening guidelines were calculated. Results: The strongest independent risk factors for GDM were a past history of GDM (OR = 10.7; 95% CI: 5.4-21.1), maternal age >= 40 years (OR 7.0; 95% CI 2.9-17.2) and BMI >= 35 kg/m2 (OR 6.1; 95% CI 3.0-12.1). The sensitivity and specificity of the NICE, ADA and ADIPS guidelines were 92.7% and 32.4%, 100% and 3.9% and 98.6% and 13.7%, respectively. Conclusions: Increasing age and BMI and previous GDM were the most significant risk factors for GDM. Current selective screening guidelines have high sensitivity but low specificity and offer little over universal screening.