Tone abnormalities are associated with maternal cigarette smoking during pregnancy in in utero cocaine-exposed infants

Objective. Maternal cigarette smoking, alcohol use, and other factors confo und studies of in utero cocaine exposure. Our goal was to determine whether in utero cocaine exposure is associated with an abnormal neurologic examin ation in infants, while controlling for concomitant cigarette smoke exposur e and other confounding variables. Design. Healthy newborns with birth weights greater than or equal to 2000 g were prospectively enrolled into a race-matched study of cocaine-exposed a nd cocaine-unexposed infants. Urine and meconium samples were analyzed for illicit drugs, the cocaine metabolite, benzoylecgonine, and the nicotine me tabolite, cotinine. A detailed neurological examination was performed at si milar to 6 weeks of age by an examiner blinded to history. Results. At 6 weeks of age, 40 cocaine-exposed infants and 56 cocaine-unexp osed infants were examined. Tone abnormalities were the only neurologic abn ormalities discovered, predominantly generalized hypertonia. Logistic model s found that maternal urine cotinine levels were predictive of an abnormal neurologic examination, whereas cocaine exposure or benzoylecgonine levels were not. No interaction was found between maternal cigarette smoking and c ocaine exposure. Race, ethanol exposure, prenatal care, homelessness, and h ead circumference were not predictive of an abnormal tone examination. The odds ratio for an abnormal examination was 2.9 (95% confidence interval: 1. 04-8.25), if the maternal urine cotinine level was >200 ng/mL. Conclusion. Our findings suggest that maternal cigarette smoking may be the major predictor of tone abnormalities reported in cocaine-exposed infants.