Predictors of Quit Attempts and Successful Smoking Abstinence in Pregnancy: An Exploratory Analysis of a Pooled Clinical Trial Dataset

Introduction: Smoking in pregnancy is a preventable cause of detrimental effects on mother and baby, exacerbating socioeconomic health disparities. This study investigates predictors of making a quit attempt and smoking abstinence in pregnancy.

Methods: This study used pooled data from two large UK multicentre smoking cessation intervention trials in pregnancy (N=1409). Baseline predictor variables included demographic, smoking behaviour and quitting belief measures. Percentage of cigarettes cut down in early pregnancy was a novel variable. Outcomes (36 weeks' gestation) were having made a quit attempt (>24 hours) and smoking abstinence (both self-reported). Exploratory logistic regression analyses, with missing smoking outcomes imputed as non-abstinent, involved univariate then multivariable analyses. Sensitivity analyses included complete case analyses, and biochemically validated abstinence.

Results: 1409 women were included in study analyses. In multivariable analyses, for making a quit attempt, higher intention to quit (OR 1.50, 95% CI 1.26 – 1.79); and higher combined self-efficacy score (OR 1.60, 95% CI 1.30 – 1.96) were statistically significant predictors. For smoking abstinence, higher percentage reduction in number of cigarettes smoked in early pregnancy (OR 1.02, 95% CI 1.01 – 1.02) and longer previous quit attempt (omnibus p =0.001) were statistically significant predictors.

Conclusions: Smoking beliefs, including motivational factors, were statistically significant predictors of making a quit attempt. However, smoking behaviours relating to cutting down the number of cigarettes in early pregnancy and having had a previous period of smoking abstinence > 6 weeks, were predictors of successful smoking abstinence.

Implications: This study adds to the evidence that motivational factors are important in initiating a quit attempt whereas positive behavioural changes are associated with smoking abstinence in pregnant women. This information could be used by clinicians designing smoking abstinence support for pregnant women. Women who reduce the number of cigarettes they smoke very early in pregnancy might be more receptive to smoking abstinence support offered at that point.