Gestational diabetes in a rural, regional centre in south Western Australia: predictors of risk.

Introduction: Gestational diabetes mellitus (GDM) is the most common antenatal complication in Western Australia. Rural areas may be at greater risk due to poorer socioeconomic status, reduced healthcare access, increased obesity and greater Aboriginal population. This paper reviews the prevalence and risk factors of GDM and outcomes for pregnancies in a regional rural centre, with a view to predicting the risk of GDM in this population, given factors identified early in the pregnancy.

Methods: Retrospective logistic regression analysis of all deliveries at Bunbury Regional Hospital (BRH) from February 2009 to March 2011 was used to produce a risk score for development of GDM.

Results: Of 1645 women delivered at BRH in the study period, nine had pre-existing diabetes and were excluded. A further 73 (4.46%) developed GDM in the current pregnancy. Logistic regression showed GDM to be strongly associated with maternal obesity (adjusted odds ratio 2.48; 95% CI 1.62-3.82), age (2.21; 1.57-3.09) lowest socioeconomic quintile (2.34; 1.23-4.22) and Asian ethnicity (3.47; 1.25-8.26). A cut-off value of 0.4 for the scoring system predicted the absence of GDM in 97.75% of women with a sensitivity of 69.9% and a predicted risk of 20.7% for GDM. Maternal outcomes showed that GDM was associated with an increased caesarean section rate (48.0% vs 30.8%; p=0.0066), lower spontaneous vaginal birth rate (37.7% vs 56.6%; p=0.048), postpartum haemorrhage (28.8% vs 17.7%; p=0.028) and longer median hospital stay (3 vs 2 days; p=0.0001). Neonatal outcomes showed a threefold increase in shoulder dystocia (10.5% vs 3.5%; p=0.025).

Conclusions: These results confirm the known association of GDM with age; obesity, lower socioeconomic quintile and Asian ethnicity are also present in the rural population. The absence of association with Aboriginal ethnicity was not expected and is discussed.