Developmental consequences of prenatal exposure to methadone.

This paper has presented evidence of growth and behavioral effects related to prenatal methadone exposure. The data suggest that methadone may have a small direct teratological effect reflected in reduced head circumference, poorer motor coordination, increased body tension, and delayed acquisition of motor milestones in methadone-exposed toddlers. In the sample as a whole, there are no direct effects of methadone exposure on mental development. However, methadone-exposed infants reared in extremely poor environmental circumstances show very delayed mental development. They function more poorly than nonexposed infants reared in such environments and more poorly than methadone-exposed infants reared in more adequate (although still economically poor) environments. This finding is important because it suggests that in the cognitive domain, methadone may not cause a behavioral deficit, but instead create a vulnerability in these children that then makes them more susceptible to impoverished environments. The results from this study indicate that a large subgroup of methadone-exposed children are clearly at risk for poor early intellectual development and that the source of the risk is to a large degree related to environmental factors. These findings suggest that preventive interventions--focused both on enriching the early experiences of such children (e.g., high-quality infant day care) and improving the quality of caregiving provided in the homes--might be particularly effective.