Newborn evaluations of toxicity and withdrawal related to prenatal cocaine exposure

The literature on prenatal cocaine exposure is unclear whether immediate postpartum effects on the infant are transient, related to either acute toxicity of cocaine, or to a withdrawal effect as cocaine is metabolized, or whether they might persist. This prospective, longitudinal study was designed to test the hypotheses that newborns urine-positive for cocaine metabolites, compared to those exposed but urine-negative, and to nonexposed controls would (1) have poorer neurobehavioral scores (toxicity effect) and (2) worsen or demonstrate less improvement over the first week (withdrawal effect). We approached over 2500 pregnant women designated to deliver at our referral hospital from public health clinics; 85% consented to participate in a longitudinal study. We excluded women <18 years old with major chronic illness and prenatal drug use except cocaine, marijuana, alcohol and tobacco. From positive urine toxicologies or admissions in private, thorough interviews, 154 were identified as prenatal cocaine users; 154 were selected from noncocaine users matched on socioeconomic status (SES), race, parity and location of prenatal care (that related to perinatal risk), for a total sample size of 308. Included in this article are the 155 surviving infants who were full-term, delivered vaginally and were well and available for testing over the first week postpartum. Infant urine specimens were collected, and neurobehavorial testing was performed by certified, blinded examiners using the Neonatal Behavioral Assessment Scale on days 1, 2-4 and 5-7 postpartum. In toxicity analyses, controlling for amount of prenatal drug exposures, only autonomic regulation demonstrated significant overall and cocaine drug group effects. Urine-positive newborns had the poorest scores (i.e., more startles, tremors). However, given that planned comparisons were not significant, these data provided little support for acute toxicity effects. In withdrawal analyses, only one significant change over time varied among exposure groups. Those infants exposed and positive for cocaine metabolites increased their scores on regulation of state on days 2-4 and decreased them on days 5-7 (when withdrawal might be evident). However, their scores on days 5-7 were not significantly lower than their initial scores, nor different from the days 5-7 scores of the exposed negatives or control infants, lending little support for withdrawal effects. Our data support those of other controlled studies in failing to demonstrate devastating early effects of prenatal cocaine exposure. They add to our understanding that effects observed do not appear to be related to acute toxicity nor to cocaine withdrawal. The uncertainty of persistent effects of cocaine exposure warrants long-term follow-up.