Smoking and obesity among pregnant women in Iceland 2001-2010

Background: The prevalence of smoking during pregnancy in Western societies has decreased in the last decades, whereas prevalence of overweight and obesity has increased. Our objective was to study secular trends and patterns of smoking and body weight among pregnant women in Iceland, during a period of dramatic changes in the nation's economy. Methods: On the basis of the Medical Birth Registry, we used a random sample of 1329 births between 1 January 2001 and 31 December 2010. Information on smoking, body mass index and background factors during pregnancy was retrieved from the Medical Birth Register and maternity records. Trends in smoking, overweight, obesity and body mass index were assessed using logistic and linear regression analyses. Logistic regression analysis was used to examine the annual odds of smoking and obesity and by socio-demographic characteristics. Results: We found a decrease in the prevalence of continued smoking during pregnancy from 12.4% in 2001 to 7.9% in 2010 [odds ratio (OR) = 0.94, 95% confidence interval (CI) (0.88-1.00)], particularly among women with Icelandic citizenship [OR = 0.92, 95% CI (0.86-0.98)], whereas no changes in obesity [OR = 1.02, 95% CI (0.96-1.07)] were observed. The highest prevalence of maternal smoking and obesity was observed in 2005-06. Conclusion: Our results indicate that smoking during pregnancy decreased among Icelandic women in 2001-10, whereas an initial increase in obesity prevalence seemed to level off towards the end of the observation period. Interestingly, we found that both of these maternal risk factors reached their highest prevalence in 2005-06, which coincides with a flourishing period in the nation's economy.