The effect of prenatal cocaine exposure on neurobehavioral outcome: a meta-analysis.

A meta-analysis was performed of the research published from 1985 to 1998 examining the effect of in utero exposure to cocaine on infant neurobehavioral outcome. The initial search for articles to include in the meta-analysis identified 18 studies with potentially meta-analytic variables. Of the studies originally retrieved, 13 failed to meet all of the inclusion criteria and were excluded from the meta-analysis. A total of 14 meta-analyses were performed comparing cocaine-exposed infants to nonexposed infants on NBAS cluster scales at birth and at 3-4 weeks of age. While the meta-analytic combination of studies produced a large enough sample size to drive statistical significance in a small majority of the tests of difference between the cocaine-exposed and nonexposed infants both at birth and soon after, the magnitude of all effects was small. The largest reliable differences appeared for the motor performance and abnormal reflexes clusters. Both also demonstrated a slight trend for increasing standard differences from birth to measures obtained at 3-4 weeks. The orientation and autonomic regulation clusters produced small, significant effects at both time periods, but the trend was for reduced effect sizes over time. All other effects appear truly negligible.