Effects of in utero substance exposure on infant neurobehavior

This study had two objectives: (1) to assess infant behavior by using the NICU Network Neurobehavioral Scale (NNNS), an assessment designed specifically for prenatally drug-exposed infants; and (2) to control for the effects of polydrug use involving alcohol, marijuana, and cigarettes on the neurobehavioral status of the newborn infant.

The subjects and controls in this study were full-term infants of appropriate gestational age with no medical problems. At 1 to 2 days of age, 20 infants exposed to cocaine, alcohol, marijuana, and cigarettes; 17 infants exposed to alcohol and/or marijuana and cigarettes; and 20 drug-free infants were evaluated by using the Neonatal Intensive Care Unit Network Neurobehavioral Scale. The data were reduced to reflect clinically defined categories of neurobehavioral function and were analyzed by using analysis of variance and chi 2 statistics.

Cocaine-exposed infants showed increased tone and motor activity, more jerky movements, startles, tremors, back arching, and signs of central nervous system and visual stress than unexposed infants. They also showed poorer visual and auditory following. There were no differences in how the examination was administered to cocaine-exposed and nonexposed infants. Reduced birth weight and length were also observed in cocaine-exposed infants.

Differences attributable to cocaine-exposed infants were related to muscle tone and motor performance, following during orientation, and signs of stress. However, cocaine-exposed infants were not more difficult to test, nor did they require an alteration in the examination. Both neurobehavioral patterns of excitability and lethargy were observed. Findings may have been due to the synergistic effects of cocaine with alcohol and marijuana.