Partner smoking influences whether mothers quit smoking during pregnancy: a prospective cohort study

Objective: To analyse the prevalence and intensity of smoking among pregnant women and their partners, and factors associated with quitting smoking among pregnant women.

Design: A prospective cohort study, starting in 2013.

Setting: Andalusia, the south of Spain.

Sample: A cohort of 486 healthy pregnant women followed-up on three occasions during pregnancy.

Methods: Estimation of the proportions of women and partners who quit smoking at each trimester.

Main outcome measures: To determine factors associated in a multivariable model, considering sociodemographic, obstetric, anthropometric, lifestyle variables, and the smoking habits of their partners.

Results: A high proportion of women quit smoking during pregnancy (61.08%; 95% confidence interval, 95% CI 53.61-68.55%). The smoking rate amongst mothers decreased from 36.06% (n = 167) before pregnancy to 14.08% (n = 65), 12.39% (n = 54), and 11.92% (n = 51) during the three pregnancy trimesters (P < 0.001), and consumption decreased from 8.71 cigarettes/day in the first trimester to 5.51 cigarettes/day in the second trimester (P < 0.001) and 5.96 cigarettes/day in third trimester (P = 0.0002 first versus third trimester). There was only a minimal decrease in the frequency of smoking among the partners, however: 38.44% (n = 178) before pregnancy, and 36.07% (n = 167), 32.72% (n = 143), and 31.85% (n = 136) during the three trimesters of pregnancy. The consumption of cigarettes did not decrease among partners: 11.75, 11.67, and 12.09 cigarettes/day (P = 0.4299 first versus second trimester; P = 0.654 first versus third trimester). Women whose partner smoked were less likely to quit (adjusted odds ratio, aOR 0.26; 95% CI 0.12-0.55).

Conclusions: About one in ten pregnant women smoked and one in four was a passive smoker. Strategies to reduce tobacco exposure in pregnancy should include a focus on partner smoking.

Tweetable abstract: Pregnant women quit smoking cigarettes in pregnancy. What about their partners?