Prenatal methadone exposure: effects on behavior in early infancy.

As part of an ongoing longitudinal study of the developmental effects of prenatal methadone exposure, 41 children born to methadone-maintained mothers and 23 children from matched backgrounds but with negative maternal history of drug abuse were evaluated at six months of age. Each child received physical and neurological examinations and a battery of behavioral assessments that included a visual habituation task, the Bayley Scales and the Object Permanence Scales. The groups did not differ significantly in frequency of suspect-abnormal neurological signs or in mean scores on the three behavioral measures. Despite the great within-group variances, performance on the behavioral measures was not related to maternal or neonatal characteristics. There were significantly more low PDI scores (predictors of developmental difficulties) among methadone subjects, particularly among methadone vs comparison males. These findings corroborate other studies that have shown 1) delayed motor development in methadone-exposed infants, 2) greater vulnerability of males to adverse environmental conditions, and 3) correlation between early methadone exposure and behavioral abnormalities in adult male rats. The significance of prenatal methadone exposure as a risk factor is discussed.