Occult maternal exposure to environmental tobacco smoke exposure.

BACKGROUND Environmental tobacco smoke (ETS) is a recognised air pollutant. Its harmful effects have been found to be implicated in health disorders, including unfavourable pregnancy outcomes. The discrepancy between self-reported environmental tobacco smoke exposure and cotinine levels in pregnant non-smokers in France was examined. METHOD Plasma cotinine was determined by a CPG-SM method on women who had answered a self-questionnaire describing their habits and environment during pregnancy. RESULTS Of 698 pregnant women reported as non-smokers, 305 (43.7%) claimed not to be exposed to ETS, yet 196 of these (64.3%) had plasma cotinine levels above the limit of detection. CONCLUSION Self-reported data on ETS exposure in pregnant women therefore underestimate actual exposure. However, cotinine assay can rectify this misclassification. An accurate identification of this risk factor will help to change attitudes towards ETS and avert its adverse effects on mother and fetus.