Prenatal narcotic exposure: perinatal and developmental effects.

Infants prenatally exposed to narcotics become passively addicted in-utero and may undergo neonatal abstinence at birth. Methadone maintenance in conjunction with intensive prenatal care for pregnant narcotic dependent women can reduce the incidence of intrauterine death, neonatal death, prematurity and its concomitant problems. However, methadone exposed infants have consistently been found to have smaller birthweights and head circumference than non-drug exposed infants. Although neonatal abstinence can be treated successfully with pharmacotherapy, the effects of in-utero narcotic exposure in the developing central nervous system are not fully understood. Infants exposed to narcotics in-utero have been found to have slit-like ventricles with smaller lateral ventricle and intracranial hemidiameter measurements during the first month of life. The incidence of strabismus is also greater in infants exposed to narcotics in-utero than the general population, but this appears to be related to lower birth weight, rather than a direct consequence of narcotic exposure. There does not appear to be developmental sequelae associated with prenatal narcotic exposure. After abstinence has abated, infants function well within the normal range of development during the first two years of life, although developmental scores may be lower than non-drug exposed comparisons groups. There are a myriad of confounding medical, pharmacological and environmental variables within this population and the relative importance of prenatal narcotic exposure in a continuum of risk factors needs to be more clearly delineated before the etiology of perinatal and developmental effects can be determined.