Abstract
BACKGROUND: While a wide range of predictors of postpartum smoking relapse have been suggested, population-based studies have rarely examined these factors exclusively among women who quit in early pregnancy. Furthermore, workplace secondhand smoke (SHS) exposure has never been examined. METHODS: We analyzed data from 10,466 pregnant women who participated in the Tohoku Medical Megabank Project Birth and Three-Generation Cohort Study. Age, education, parity, breastfeeding, postpartum depression, SHS exposure at home, and SHS exposure at work (not working, working without SHS exposure, working with SHS exposure) were evaluated as possible predictors. Multiple logistic regression analyses were conducted to examine the associations between these factors and smoking relapse by 1 year postpartum among women who quit in early pregnancy. Analyses stratified by SHS exposure at home were also conducted. RESULTS: About one-fourth of early-pregnancy quitters had relapsed into smoking by 1 year postpartum. Lower education, multiparity, not breastfeeding, postpartum depression, and SHS exposure at home were associated with increased risks of smoking relapse. Working with SHS exposure was associated with an increased risk of smoking relapse; the multivariate-adjusted odds ratios of working without SHS exposure and working with SHS exposure compared with not working were 1.14 (95% confidence interval [CI], 0.82-1.59) and 2.18 (95% CI, 1.37-3.46), respectively. The significant association of workplace SHS exposure was observed only among women without SHS exposure at home. CONCLUSION: SHS exposure at work, as well as education, multiparity, breastfeeding, postpartum depression, and SHS exposure at home were associated with postpartum smoking relapse among early-pregnancy quitters.