The impact of Aboriginal status, cigarette smoking and smoking cessation on perinatal outcomes in South Australia.

OBJECTIVE To assess the impact of Aboriginal status, active cigarette smoking and smoking cessation during pregnancy on perinatal outcomes. DESIGN Retrospective cohort study from 1 January 1999 to 31 December 2008. SETTING All singleton births in South Australia. PARTICIPANTS Population-based birth records of pregnancies to Aboriginal women (n = 4245) and non-Aboriginal women (n = 167 746). MAIN OUTCOME MEASURES Adjusted odds ratios (aORs) and 95% CIs for adverse maternal and neonatal outcomes according to Aboriginal status and maternal smoking in pregnancy. RESULTS Active cigarette smoking during pregnancy was associated with an increased risk of adverse perinatal outcomes, including premature labour (Aboriginal, 1-10 cigarettes per day: aOR, 1.69; 95% CI, 1.28-2.23; non-Aboriginal, 1-10 cigarettes per day: aOR, 1.46; 95% CI, 1.34-1.58), preterm birth (Aboriginal, 1-10 cigarettes per day: aOR, 1.40; 95% CI, 1.14-1.73; non-Aboriginal, 1-10 cigarettes per day: aOR, 1.48; 95% CI, 1.39-1.57), intrauterine growth restriction (Aboriginal, 1-10 cigarettes per day: aOR, 2.33; 95% CI, 1.77-3.08; non-Aboriginal, 1-10 cigarettes per day: aOR, 2.65; 95% CI, 2.48-2.83) and small for gestational age (Aboriginal, 1-10 cigarettes per day: aOR, 2.49; 95% CI, 2.06-3.00; non-Aboriginal, 1-10 cigarettes per day: aOR, 2.29; 95% CI, 2.20-2.40). For both Aboriginal and non-Aboriginal women who smoked 11 or more cigarettes per day the aOR for these outcomes increased. Smoking cessation in the first trimester reduced these risks to levels comparable with non-smokers. The risk of each adverse outcome was greater in Aboriginal than non-Aboriginal women for all smoking categories; however, interactions between Aboriginal status and smoking were not significant, indicating an equal contribution of smoking to poor outcomes in both populations. CONCLUSIONS Smoking cessation or reduction during pregnancy would significantly improve outcomes in both Aboriginal and non-Aboriginal women. This should be made a clear priority to improve pregnancy outcomes for all women.