Smoking habits among pregnant women in a Norwegian county 1987-1994

Background. The aim of the study was to investigate changes in smoking habits among pregnant women in the city of Trondheim and its surroundings. We also wanted to register the effect of a national campaign against smoking in pregnancy introduced in December 1989. Material and methods. From 1987-1994 midwives interviewed 21 348 women in a nonselected population during a routine ultrasound examination at 18 weeks of pregnancy. Smoking habits and cigarette consumption were recorded. Results. The point prevalence smoking rate among pregnant women decreased from 34% in 1987 to 22% in 1994 (p<0.001). A stratified analysis indicated that the reduction was not confounded by changes in age and parity over time. The mean number of cigarettes per pregnant smoker decreased from 8.6 cigarettes per day to 7.0 cigarettes per day during the study period (p<0.001). In 1987, 49% of the pregnant smokers consumed greater than or equal to 10 cigarettes per day compared with 35% in 1994 (p<0.001). The national campaign may have reinforced the on-going decline in smoking rate, but no significant effect was observed. Conclusions. The study demonstrated a statistically significant reduction in smoking prevalence among pregnant women in the study area. A similar decrease was not observed among women in the general population. No significant effect of the national campaign against smoking during pregnancy was observed.