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 e xamining the effect of in utero exposure to cocaine on infant neuobehaviora l outcome. The initial search for articles to include in the meta-analysis identified 18 studies with potentially meta-analytic variables. Of the stud ies originally retrieved, 13 failed to meet all of the inclusion criteria a nd were excluded from the meta-analysis. A total of 14 meta-analyses were p erformed comparing cocaine-exposed infants to nonexposed infants on NBAS cl uster scales at birth and at 3-4 weeks of age. While the meta-analytic comb ination of studies produced a large enough sample size to drive statistical significance in a small majority of the tests of difference between the co caine-exposed and nonexposed infants both at birth and soon after, the magn itude of all effects was small. The largest reliable differences appeared f or the motor performance and abnormal reflexes clusters. Both also demonstr ated a slight trend for increasing standard differences from birth to measu res obtained at 3-4 weeks. The orientation and autonomic regulation cluster s produced small, significant effects at both time periods, but the trend w as for reduced effect sizes over time. All other effects appear truly negli gible. (C) 1999 Elsevier Science Inc. All rights reserved.