OPPOSING PLACENTAL GRADIENTS FOR THIOCYANATE AND COTININE AT BIRTH

In order to compare maternal and fetal exposure to compounds of tobacc o smoke at the end of pregnancy, concentrations of cotinine and thiocy anate were measured in cord serum and maternal serum collected from 24 daily smoking and four non-smoking women at the time of child birth, The median level of thiocyanate (69 mu mol/l) in maternal serum was ab out 50% higher than the median level (47 mu mol/l) in cord serum (P < 0.0001) (Wilcoxon matched-pairs signed-ranks test), On the other hand, the median level of cotinine (22 ng/ml) in maternal serum was less th an half of the median level (51 ng/ml) in cord serum (P = 0.0009), The correlation between maternal and cord serum was 0.77 (P < 0.0001) (Sp earman's rank correlation coefficient) for thiocyanate levels and 0.90 (P < 0.0001) for cotinine, The high correlation between measurements of cotinine in maternal serum and cord serum indicates that maternal c otinine levels can be used to describe interindividual differences in fetal exposure to tobacco smoke, The placental gradients for cotinine and thiocyanate may indicate differences in maternal and fetal exposur e to products of tobacco smoke.