Level of prenatal cocaine exposure and 48-month IQ: importance of preschool enrichment.
This analysis was designed to determine whether prenatal cocaine exposure is related to children's standardized cognitive test scores at age 4 years after control for relevant covariates. Masked examiners using the WPPSI-R assessed ninety-one 4-year-old children with prenatal cocaine exposure and 79 children of comparable demographic background who were not exposed. Level of cocaine exposure was documented by postpartum interviews of mothers and assays of the infants' meconium. Prenatal cocaine exposure, analyzed as exposed/unexposed or as an ordinal dose variable, was not associated in bivariate or multivariate models with decrements in full-scale IQ, performance IQ, verbal IQ, or in any of the subtests. In bivariate analyses, we found significant differences between exposure groups defined as "unexposed", "lighter", and "heavier" in mean scores of the WPPSI-R subtests Object Assembly (P=0.04) and Picture Completion (P=0.03). For these scores, children with heavier exposure attained higher scaled scores. Birth mother's education and child's experience with preschool enrichment were both associated with higher verbal IQ scores. These findings suggest that prenatal cocaine exposure does not exert negative effects on the cognitive competence of preschool-aged children. Children with a history of prenatal cocaine exposure benefit from preschool programs that have been shown to enhance outcomes for other low-income children.