Maternal smoking and smoking in the household during pregnancy and postpartum: findings from an Indigenous cohort in the Northern Territory.

OBJECTIVE: To describe the trends in maternal smoking and smoking in the household for a cohort of Indigenous women followed from late pregnancy to 7 months postpartum. DESIGN AND
SETTING: Prospective cohort study embedded within a randomised controlled trial (RCT) performed in the Northern Territory involving participants recruited between 30 June 2006 and 4 May 2010. PARTICIPANTS: 215 Indigenous women aged 17-39 years who had been recruited into the RCT, 162 of whom had completed their last study visit at 7 months postpartum by 1 June 2010. MAIN OUTCOME MEASURES: Smoking status of women, and smoking within their households, in their third trimester, and at 1 month, 2 months and 7 months postpartum.
RESULTS: There were complete data on women's smoking status for 121 participants. Among these, the self-reported smoking rate was 45% (95% CI, 36%-55%) during pregnancy, increasing to 63% (95% CI, 54%-71%) at 7 months postpartum. Of the 66 women who were non-smokers at the antenatal visit, 23 (35%; 95% CI, 23%-47%) were smoking by the time their baby reached 7 months of age. Thirty-one per cent (95% CI, 23%-39%) of households included people who smoked inside during the antepartum period, whereas 16% (95% CI, 10%-23%) included people who smoked inside at 7 months postpartum.
CONCLUSIONS: While an apparent reduction in indoor exposure to tobacco smoke during the postpartum period is encouraging, this is offset by an increase in the proportion of antenatal non-smokers who subsequently reported smoking after the birth of their child. More health care service delivery and research attention needs to be directed to smoking during pregnancy and to postpartum relapse in this population.