Does stage-based smoking cessation advice in pregnancy result in long-term quitters? 18-Month postpartum follow-up of a randomized controlled trial

Aims: To evaluate the effect on quitting smoking at 18 months postpartum of smoking cessation interventions based on the Transtheoretical Model (TTM) delivered in pregnancy compared to current standard care. It has been claimed that TTM-based interventions will continue to create quitters after the end of the intervention period. Design: Cluster randomized trial. Setting: Antenatal clinics in general practices in the West Midlands, UK. Participants: A total of 918 pregnant smokers originally enrolled in the trial, of which 393 women were followed-up at 18 months postpartum. Interventions: One hundred general practices were randomized into the three trial arms. Midwives in these practices delivered three interventions: A (standard care). B (TTM-based self-help manuals) and C (TTM-based self-help manuals plus sessions with an interactive computer program giving individualized smoking cessation advice). Measurements: Self-reported continuous and point prevalence abstinence since pregnancy. Findings: When combined together, there was a slight and not significant benefit for both TTM arms compared to the control, with an odds ratio (OR) 95% confidence interval (CI) of 1.20 (0.29-4.88) for continuous abstinence. For point prevalence abstinence, the OR (95%CI) was 1.15 (0.66-2.03). Seven of the 54 (13%) women who had quit at the end of pregnancy were still quit 18 months later, and there was no evidence that the TTM-based interventions were superior in preventing relapse. Conclusions: The TTM-based interventions may have shown some evidence of a short-term benefit for quitting in pregnancy but no benefit relative to standard care when followed-up in the longer-term.