The aim of this paper is to investigate the distribution of smoking cessation during pregnancy in relation to sociodemographic and professional characteristics. The study population are, primiparous or secundiparous women who gave birth in a large public hospital in the city of Valencia (Spain) and who have carried out paid work during pregnancy. A sample of 593 women were personally interviewed in the maternity hospital. A simple analysis was carried out on the data subsequently adjusting a logistic regression model. Sixty-two per cent of the women smoked before pregnancy. Of them, 28% gave up smoking during pregnancy. Giving up smoking during pregnancy is more common among women of between 26-30 years of age (ORadjusted = 2.1), those with secondary level of education (ORadjusted = 2.6) and among those for whom daily cigarette intake before pregnancy was between 1-9 cigarettes (ORadjusted = 12.3) or between 10-19 (ORadjusted = 2.7). The modification of smoking during pregnancy requires interventions prior to and throughout the course of pregnancy which should be aimed at risk groups such as younger women, those less educated and heavy smokers.