Methadone exposure in utero: developmental status at one and two years of age.

The developmental status of infants exposed to methadone in utero and non-drug exposed infants was assessed at one and two years of age. Fifty-three 12-month old infants (26 drug exposed and 27 controls) and forty-one 24-month old infants (17 drug exposed and 24 controls) were assessed with the Bayley Scale of Mental Development and a neurological exam. Neurologicals for all infants were normal. At twelve months of age the Mental Developmental Index (MDI) was within the normal range for both groups although the scores for the drug exposed group were significantly lower. There was no difference in the MDI between Family Center and control infants at 24-months of age. Differences were found, however, in the failure rates of specific items. The implications of these findings for delineating the effects of methadone exposure in utero are discussed.