Newborns' cord blood plasma cotinine concentrations are similar to that of their delivering smoking mothers

Background: In utero exposure to constituents of tobacco smoke has perinatal and postnatal health consequences. Umbilical cord plasma cotinine levels have been shown to correlate with self-reported daily number of cigarettes at the end of pregnancy, but the exact relationship between maternal and newborn plasma cotinine (and nicotine) is unknown. Methods: Concentrations of cotinine, nicotine's main metabolite, were determined in venous blood of delivering mothers and in arterial umbilical cord blood of their newborns at birth. Data from eighteen mother-newborn dyads were analyzed. Results: The mothers smoked 95.1 (SD = 96, range 10-420) cigarettes the week preceding delivery. Their mean plasma cotinine concentration at delivery was 106 ng/mL (SD = 53, range 17-245) and the newborns' mean umbilical cord plasma cotinine was 881.2ng/mL (SD=53, range 10-198, p<0.001). The difference can be explained by the elimination time of around 6 h which occurred between sampling in mothers and in umbilical cord blood. Arterial umbilical cord blood plasma cotinine was highly associated with that of the smoking mothers: y = 0.79x + 0.97, Rsq = 0.95, p<0.001. Conclusions: Maternal and newborn plasma cotinine concentrations are strongly associated. There is probably no placental barrier for plasma cotinine between pregnant mothers and their newborns. Lack of a placental barrier for cotinine (and probably nicotine) can partially explain smoking related perinatal disorders. (C) 2009 Elsevier Ireland Ltd. All rights reserved.