Smoking cessation during pregnancy: Testing a psycho-biological model

The study set out to assess the power of three sets of variables to discriminate between women who continued or quit smoking in the early stages of pregnancy: social and demographic; nicotine dependence; and constructs of the theory of planned behaviour (TPB). A cross-sectional design was employed in which women identified as quitters or smokers during the early stages of pregnancy completed measures of concurrent attitudes, social norms, behavioural control, demographic variables and retrospective measures of nicotine dependence. Women were approached during their first pre-natal hospital appointment. Seventy-one women who reported smoking prior to their pregnancy were asked to take part in the study. Sixty-five of these agreed: 44 smokers, 21 quitters. Having a partner who smoked was associated with continued smoking. In addition, three sets of TPB variable scores differed according to group status: social norms relating to friends (but not partner), attitudes relating to child harm, and control beliefs. Stepwise logistic regression found the latter two variables to accurately categorize 95% of the participants. However, hierarchical regression into which a measure of nicotine dependence was forced before the TPB variables found these variables to not add to the power of the logistic regression beyond that explained by the measure of dependence. While smoking cessation during pregnancy may be consequent to cognitive processing suggested by the TPB, these data cannot exclude the possibility that the primary determinant of cessation is the extent of nicotine dependence and cognitions form a post hoc rationalization rather than having a causal role.