Do pregnant women who report a reduction in cigarette consumption consume less tobacco?

OBJECTIVE

To investigate the relationship between changes in self-reported cigarette consumption and changes in serum thiocyanate among pregnant and non-pregnant women who participated in a smoking cessation trial.

DESIGN

Intervention study.

SETTING

General practitioners in western Norway.

SUBJECTS

146 pregnant and 102 non-pregnant women who were daily smokers at inclusion. Self-reported cigarette consumption and serum thiocyanate were recorded at inclusion and after 12 months.

RESULTS

Women who smoked in the first trimester of pregnancy reported 21% less cigarette consumption than non-pregnant women. This was in accordance with the serum thiocyanate values. Twelve months later the mean values of serum thiocyanate had increased irrespective of whether the postpartum women reported that they had reduced, increased, or not changed their cigarette consumption. However, among those who reported that they had stopped smoking, analyses of serum thiocyanate confirmed their statements, with very few exceptions. Among nonpregnant women, the serum thiocyanate changed in accordance with the reported changes in cigarette consumption in all groups.

CONCLUSION

Women smoking daily in the first trimester of pregnancy had a lower exposure to tobacco than daily smoking non-pregnant women. Twelve months later (six months after delivery) analyses of serum thiocyanate indicated that postpartum women underestimated their tobacco consumption.