Social Predictors of Continued and Indoor Smoking Among Partners of Non-smoking Pregnant Women: The TMM BirThree Cohort Study

BACKGROUND: Secondhand smoke (SHS) from partners is a major source of exposure for non-smoking women. However, epidemiological studies have rarely examined social factors associated with continued and indoor smoking among pregnant women’s partners. METHODS: We analyzed data on 6,091 partners of non-smoking pregnant women in the Tohoku Medical Megabank Project Birth and Three-Generation Cohort Study. Partners’ age, education, income, workplace SHS exposure (almost never or sometimes, almost every day), and pregnant women’s smoking history (never, quit before pregnancy awareness, quit after pregnancy awareness) were used as social factors. Multiple logistic regression analyses were conducted to examine the associations of social factors with partners’ continued smoking and indoor smoking. RESULTS: Among 2,432 smoking partners, 2,237 continued to smoke after pregnancy awareness. Workplace SHS exposure was associated with increased risk of partners’ continued smoking: the odds ratio of workplace SHS exposure almost every day compared with almost never or sometimes was 2.08 (95% confidence interval, 1.52–2.83). Women’s quitting smoking after—but not before—pregnancy awareness was associated with decreased risk of partners’ continued smoking: the odds ratio of women’s quitting after pregnancy awareness compared with never smoking was 0.57 (95% confidence interval, 0.40–0.80). About one-third of partners who continued to smoke did so indoors. Older age, lower education, workplace SHS exposure, and women’s quitting smoking after pregnancy awareness were associated with increased risk of partners’ indoor smoking. CONCLUSIONS: Workplace SHS exposure and pregnant women’s smoking history were associated with continued smoking and indoor smoking among partners of non-smoking pregnant women.