[Determinant factors of smoking cessation during pregnancy]

To investigate sociodemographic factors and smoking habit characteristics associated with spontaneous smoking cessation during pregnancy.

Cross-sectional study including 726 pregnant smoking women who attended the antenatal clinic of the Vall d'Hebron University Hospital in Barcelona between July and December 1997 and who agreed to participate were studied. Information was obtained by a structured questionnaire which included items on age, educational level, marital status, previous and current smoking habit, partner smoking habit and partner's attitude towards the smoking habit of the pregnant woman.

At the first antenatal visit, 19.7% of women had given up smoking spontaneously. Light smokers (between 1 and 9 daily cigarettes; OR = 4.74) or moderate smokers (between 10 and 19 daily cigarettes; OR = 2.20) were more likely to stop smoking compared to heavy smokers (more than 20 daily cigarettes). If the partner did not smoke, smoking cessation was more likely among pregnant women (OR = 1.78). At the first antenatal visit, among those women who carried on smoking during pregnancy, there was a significative reduction in cigarette consumption of about half the usual daily number of cigarettes smoked.

One out of five pregnant women give up smoking spontaneously during pregnancy from the moment they know they were pregnant until the first antenatal visit. Women who are less likely to stop smoking during pregnancy are those who smoke a larger number of cigarettes. Family environment is an important influential factor in the smoking habit of the pregnant woman.