Interpreting research on prenatal substance exposure in the context of multiple confounding factors.

Fetal exposure to specific drugs often occurs in the context of polydrug use, medical complications, and social/environmental risks. Early reports of severe developmental consequences of fetal exposure to illicit drugs, for example, cocaine, have largely been unsupported by recent studies that take these factors into account. Using a database of published studies on cocaine exposure, this article examines how confounding factors are controlled by recruitment and statistical strategies. Rather than attempting to reduce the impact of these factors, it is suggested that multiple risks in children's lives should be included in models of developmental outcomes along with drug exposure. Understanding the complexity of multiple risks in the child's environment and the subtlety of drug exposure effects can guide the choice of clinical treatment and intervention.