To study the developmental effects of prenatal exposure to opiates, a prospective follow up study of 34 drug-exposed (opiates and nicotine) and 42 reference infants (nicotine exposure only) was conducted from January 1992 to September 1995. At the time of delivery, 12 of 34 mothers used opiates without medical control. Twenty-two mothers participated in a methadone maintenance programme. At 1 year, the average Griffiths Developmental Quotient (DQ) was lower in the drug-exposed group (mean: 100.5 vs. references 107.9; P < 0.001). This difference was mainly due to lower subscales "locomotor" (mean 100.8 vs. 111.4; P < 0.05) and "intellectual performance" (mean 100.8 vs. 108.5; P < 0.05) in the drug-exposed group. Severe developmental retardation mean DQ (-2 SD) was diagnosed in 2 drug-exposed infants. Mild developmental retardation (mean DQ: 1 SD- > 2 SD) was found in 7 drug-exposed and in 3 reference infants (P < 0.05). Neurological abnormalities were found more frequently in the drug-exposed group (11 vs. 3 infants; P < 0.01). Among the opiate-exposed infants, the subscales "hearing and speech" and "intellectual performance" were lower in the uncontrolled drug-using than in the methadone group. The 17 fostered infants showed no difference in developmental outcome compared with the 10 infants living with their biological parents (mean DQ: 100.0 versus 101.3).
Conclusions: At 1 year infants prenatally exposed to opiates are at risk for mild psychomotor developmental impairment.