A randomized controlled trial of a smoking cessation intervention during pregnancy

This study was a randomized controlled trial of a smoking cessation intervention for pregnant smokers. Women who reported smoking at their first antenatal visit and satisfied the inclusion criteria were asked to participate in the trial. Analysis was restricted to 393 evaluable women in the control group (received usual antenatal care) and 339 women to the study group (received usual antenatal care plus the intervention). The primary hypotheses were that the intervention would result in a higher proportion of quitters and that the mean birth-weight of babies born to women receiving the intervention would be greater than that of babies born to women in the control group. The outcome measures were smoking status based on self-report combined with a urinary cotinine level of <115 ng/mL, and birth-weight. There was no significant difference in quit rate between women receiving the intervention and women in the control group (11.9% versus 9.8% p=0.41). Babies born to women receiving the intervention were on average 84 g heavier than babies born to controls (p=0.04). The factors that contribute to the lack of a significant increase in smoking cessation in the intervention group and the possible explanation for the changes in birth-weight are discussed.