Primary prevention of cancer. Smoking cessation in general practice. An intervention study among women who smoke.

The material includes the smoking habits of 2,393 pregnant women who went for prenatal check-ups at 185 general practitioners in 1987. 45% were daily smokers in the last 3 months before pregnancy and 38% were still daily smokers in the first trimester of pregnancy. Younger pregnant women smoked more than older women. Smoking habits changed little with the number of previous pregnancies. 538 pregnant daily smokers were included in an intervention study and followed throughout pregnancy and for one year after birth. 96% of the pregnant women were motivated to change their smoking habits. The pregnant women as a group reduced their smoking habits (measured in the number of cigarettes per day) by 25%. 10% of those who smoked at the 1st prenatal check-up stopped smoking later in the pregnancy. The material includes a questionnaire filled in by the pregnant women in the first trimester and a new questionnaire filled in by the same women one year after the birth. The material was collected in the period 1986 to 1989 and the project was financed by the Norwegian Cancer Society. The control material includes 450 non-pregnant women who were recruited and studied over the same period.