Aims: To investigate the smoking prevalence the last three months before pregnancy and at 18 weeks of gestation among women in Norway and to evaluate the impact of pre-pregnancy smoking habits, maternal age, level of education, civil status and parity on smoking cessation.
Material and methods: A prospective, multicenter survey. The study population included 4 766 pregnant women who attended a routine ultrasound examination at 18 weeks of pregnancy in six Norwegian hospitals during the period from September 1994 to March 1995. Smoking habits before and during pregnancy were recorded.
Results: The point prevalence of self-reported daily smoking among the women three months before the pregnancy was 34%. At 18 weeks of pregnancy, 21% of the women reported smoking daily (p<0.001). A multiple logistic regression analysis revealed that a low number of cigarettes smoked per day during the last three months before pregnancy was the best predictor for smoking cessation. Educational level, maternal age, parity and civil status were also statistically significant contributors to smoking cessation. Eighty percent of the women who were unable to stop smoking, reported a reduction in cigarette consumption. The mean number of cigarettes per day was reduced from 13.9 before pregnancy to 7.3 at 18 weeks of pregnancy (p<0.001).
Conclusion: In a national survey, 21% of the pregnant women reported smoking daily in the second trimester. Thirty-eight percent of the women who were daily smokers before the pregnancy stopped smoking in early pregnancy. A low cigarette consumption prior to the pregnancy was the best predictor for smoking cessation.