[Cotinine levels in serum and colostrum of smoking puerperae].

In 50 women (25 smokers and 25 non-smokers), cotinine, a relatively stable metabolite of nicotine, was measured in the 3rd postpartum day in blood serum and colostrum by means of enzyme-enhanced chemiluminescence. Non-smokers had cotinine levels in serum and colostrum below 10 ng/ml. Colostrum cotinine content in smokers amounted to approximately 50% of the respective serum level and both these values were strongly positively correlated (p < 0.0014). Cotinine level in early breast-milk did not correlate significantly with the number of cigarettes smoked daily by a mother. Newborns breast-fed by smoking women are exposed to the tobacco smoke compounds not only by an environmental ("passive") smoking but also by the ingestion of nicotine metabolites present in mother's milk.