Long-term maintenance of smoking cessation in pregnancy: an analysis of the birth cohort generation XXI.

INTRODUCTION: Pregnancy affords opportunities for health promotion and disease prevention. We worked with a population-based cohort of women who gave birth in Portugal to quantify the proportion of women who quit smoking during pregnancy, the proportion of these women who continued to abstain 4 years after delivery, and the determinants of these outcomes.
METHODS: A birth cohort was assembled in public maternity units of Porto, Portugal, in 2005-2006, and all women were reevaluated at an average of 4 years after delivery. A total of 5,420 mothers were included in the analysis. Smoking status at baseline and at follow-up was ascertained by interview. Adjusted prevalence ratios and 95% CIs were computed using robust Poisson regression.
RESULTS: Overall, 47.4% of women who smoked ceased smoking and 41.7% reduced cigarette consumption during pregnancy. Four years after delivery, 32.1% of those who stopped smoking during pregnancy continued to abstain. Older women, first-time mothers, light smokers, those who were living with a partner at the time of follow-up, those who became pregnant again after the index pregnancy, those who breast fed for more than 52 weeks, and those with a child diagnosed with asthma and/or rhinitis were more likely to abstain from smoking.
CONCLUSIONS: Approximately half of all women stopped smoking during pregnancy and, among these, approximately one third continued to abstain 4 years after delivery. The high proportion of relapse may be attributable to poor awareness or skepticism regarding the adverse effects of secondhand smoke on children or physiological and psychological dependence on nicotine.