Do pregnant women still smoke?: A study of smoking patterns among 261,029 primiparous women in Denmark 1997-2005

Objective. Describe smoking patterns in pregnancy in Denmark from 1997 to 2005 and make comparisons with the other Nordic countries, and further to analyze the influence of socio-demographic factors on smoking patterns in pregnancy. Design. Register-based study. Setting. Denmark. Population. All primiparous women giving birth in Denmark (n=261,029) in the period 1997-2005. Methods. Information about deliveries, smoking status and characteristics of the women were retrieved from the Danish National Birth Registry. Multiple logistic regression analysis was used to assess the importance of different factors in relation to the risk of smoking in pregnancy. Main outcome measures. Odds Ratios and associated 99% confidence intervals were used to assess the risk of smoking in pregnancy. Results. The prevalence of women who smoked at some point in pregnancy declined significantly from 22% in 1997 to 16% in 2005. However, among women younger than 20 years at delivery, the pregnancy-related smoking prevalence increased from 37 to 43%. Time trends in smoking patterns were not confounded by socio-demographic factors. Women living in rural areas and women who did not have a partner had the highest risk of smoking in pregnancy. Conclusions. In this nationwide survey, a significant decline in the prevalence of primiparous women who smoked during pregnancy was observed from 1997 to 2005. Despite of this, pregnancy-related smoking prevalence in Denmark is still higher than in the other Nordic countries. Furthermore, the proportion of pregnant smokers was highest among young women, and future smoking cessation programs should bring this subgroup of women into focus.