Maternal smoking during pregnancy and the risk of childhood type 1 diabetes in Western Australia

The aim of this study was to investigate the association between maternal smoking during pregnancy and type 1 diabetes in the offspring, using complete population data sources available in Western Australia. A prospective cohort study was undertaken with cases defined as children born in Western Australia between 1998 and 2008 who were diagnosed with type 1 diabetes at < 15 years of age up to 31 December 2010. Eligible cases were identified from the prospective, population-based Western Australian Children's Diabetes Database. Record linkage was performed to identify perinatal records of cases from the Western Australian Midwives' Notification System, which contains data on > 99% of all births in Western Australia. Cox regression was used to analyse the data and adjust for recognised risk factors such as birthweight, gestational age, maternal age and socioeconomic status. The unadjusted HR for babies born to mothers who smoked during pregnancy being diagnosed with childhood type 1 diabetes was 0.70 (95% CI: 0.50, 0.97). After adjustment, the confidence interval widened but the point estimate remained relatively unchanged at 0.76 (95% CI: 0.54, 1.08). Analyses of data from this population-based study indicate that maternal smoking during pregnancy may be associated with a reduced risk of childhood type 1 diabetes. Further investigation in larger populations with more detailed smoking data could lead to novel hypotheses regarding mechanisms that influence the immunopathogenesis of type 1 diabetes in early life.