Factors that influence changes in smoking behaviour during pregnancy

This study explored characteristics of women who continue to smoke beyond the first trimester of pregnancy.

A cohort of 1283 pregnant women were surveyed at the time they registered with a maternity care provider, using a postal questionnaire. Women who reported they were ex-smokers were asked when they had stopped smoking. Data were analysed using logistic regression to identify socio-demographic variables associated with smoking and with stopping smoking.

829 (69.2%) women responded to the questionnaire. 183 (22.2%) reported smoking when they became pregnant. Forty nine (26.8%) of the women smoking at conception reported giving up in the first trimester. Factors significantly associated with stopping smoking in the first trimester were current employment (OR 2.37, 95% CI 1.16-4.85), first pregnancy (OR 2.18, 95% CI 1.11-4.28), and experiencing nausea during the pregnancy (OR 2.59, 95% CI 1.11-6.04). Women who held a community services card (OR 0.41, 95% CI 0.19-0.86), Maori women (OR 0.38, 95% CI 0.15-0.98) and women whose partners smoked (OR 0.35, 95% CI 0.17-0.70) were significantly less likely to have stopped smoking.

Socioeconomically deprived women were more likely to continue to smoke beyond the first trimester of pregnancy and this needs to be taken into account in the provision of smoking cessation support.