FETAL EXPOSURE TO TOBACCO-SMOKE PRODUCTS - A COMPARISON BETWEEN SELF-REPORTED MATERNAL SMOKING AND CONCENTRATIONS OF COTININE AND THIOCYANATE IN CORD SERUM

Background: The objective of the study was to assess the relationship between maternal smoking habits and biomarkers of tobacco smoke measur ed in cord serum. Methods: The study population comprised 102 mothers. 32 daily smokers, 24 occasional smokers and 136 nonsmokers. Informati on on maternal smoking habits was collected in a self-administered que stionnaire at birth and compared with cotinine and thiocyanate concent rations in cord serum. Results: In linear regression analysis, a unit increase in daily cigarette smoking corresponded to a 4.4 ng/ml (95% C I: 1.1-7.6) increase in cotinine concentration and 2.3 mu mol/l(0.8-3. 8) in thiocyanate. A cut-off point of 14 ng/ml cotinine separated well between daily smokers (88% above) and nonsmokers (96% below), but rev ealed a classification problem in occasional smokers (46% above). Conc lusion: Cord serum cotinine and thiocyanate concentrations are related to daily smoking rate during pregnancy, but these concentrations vary considerably among occasional smokers. Detailed information on smokin g habits is the key issue in understanding the adverse fetal effects o f occasional smoking during pregnancy.