Birth outcome from a prospective, matched study of prenatal crack/cocaine use: II. Interactive and dose effects on neurobehavioral assessment.

OBJECTIVE: This prospective, longitudinal project was designed to determine the effects of prenatal cocaine use on the neurodevelopmental outcomes of infants from a historically understudied rural public health population.
METHODOLOGY: We interviewed > 2500 women prenatally, identified 154 cocaine users, and matched 154 controls on race, parity, socioeconomic status, and location of prenatal care (that related to level of pregnancy risk). Drug testing was required at enrollment and at delivery; detailed demographic, psychosocial, and drug histories were taken at each available trimester and follow-up visit. After birth, certified evaluators, blinded to maternal history of drug use, administered the Brazelton Neonatal Behavioral Assessment Scale (BNBAS) under controlled conditions. Evaluation time for preterm infants was adjusted for gestational age.
RESULTS: After controlling for the effects of marijuana (users of other illicit drugs were excluded), alcohol, and tobacco use, the following results remained. There were significant drug group interactions on the BNBAS Qualifier Score of Alert Responsiveness that demonstrated lower scores among infants who were exposed to both cocaine and tobacco and among those exposed to both marijuana and tobacco. There were also significant correlations between the amount of cigarette, alcohol, marijuana, and cocaine exposure and several BNBAS scores. The reported amount of cocaine use in the third trimester was negatively related to scores of Orientation, Cost of Attention, and Alert Responsiveness (that was also related to amount of cocaine used over the entire pregnancy). When the effects of marijuana, alcohol, and tobacco were partialled out, the amount of cocaine use in the third trimester was negatively related to Regulation of State, a precursor of alertness, and the infant's ability to orient to the environment.
CONCLUSIONS: The observed decrement in state regulation, attention, and responsiveness among cocaine-exposed neonates raises concerns about later developmental abilities as well as the effect these infants may have on caregivers (who themselves may be compromised in their parenting abilities by their drug use). Follow-up of these infants will reveal if these disadvantages continue. These early results also emphasize the importance of considering amount and time of drug exposure as well as the interactive effects of drug exposure and other risk variables.