Prenatal tobacco exposure, biomarkers for tobacco in meconium, and neonatal growth outcomes

Objective: To assess relationships between marker concentrations of tobacco in meconium and weekly self-reported maternal cigarette consumption, and prediction of neonatal growth outcomes. Study design: Pregnant mothers (n = 119) from a longitudinal maternal smoking and infant neurobehavioral study (Behavior and Mood in Babies and Mothers [BAM BAM]) provided daily tobacco smoking histories. Nicotine, cotinine, and trans-3′-hydroxycotinine concentrations were quantified in 111 neonatal meconium specimens by liquid chromatography-tandem mass spectrometry. Results: Median self-reported third trimester smoking was 5.9 cigarettes per day among smokers. Meconium samples from infants born to non-smokers (n = 42) were negative for tobacco markers, while specimens from self-reported smokers (n = 41) were positive for (median, range) nicotine (50.1 ng/g, 3.9-294), cotinine (73.9 ng/g, 6.4-329), and trans-3′-hydroxycotinine (124.5 ng/g, 10.2-478). Quitters (n = 28) self-reported stopping smoking at gestational weeks 2-39. Four meconium specimens from quitters were positive for tobacco biomarkers. Reduced birth weight, length, and head circumference significantly correlated with presence of meconium markers but not with individual or total marker concentrations. Among quitters and smokers, reduced infant birth weight, head circumference, and gestational age correlated with total and average daily cigarette consumption in the second and third trimesters. Conclusion: Smoking cessation or reduction during pregnancy improved neonatal outcomes. The window of detection for tobacco in meconium appears to be the third trimester; however, low exposure in this trimester failed to be detected. These results will aid physicians in educating women who are pregnant or thinking about becoming pregnant on the negative consequences of smoking during pregnancy. In addition, infants at risk can be identified at birth to assist early intervention efforts.