THE IMPACT OF PRENATAL DRUG EXPOSURE ON THE NEONATE

The effects of various social drugs on the fetus are diverse in their physiologic, teratogenic, and developmental consequences. This is the result of potential differences in the timing of exposure to the drug (or drugs), the intensity (or dose) of exposure, the chronicity in which the exposure occurs, as well as possible interactional effects of polydrug use during gestation. Different organs have different periods of vulnerability during gestation, such that a fetus exposed to a drug during the 12th week may have more profound sequelae than the fetus exposed at 37 weeks' gestation. The fetus has limited capacity to metabolize and excrete compounds; thus, the pharmacokinetics of a drug in the fetus differ significantly from that in the mother. Similarly, the newborn infant may continue to have clinical levels of a drug for hours to days after birth, with withdrawal from the drug in evidence long after the infant has been discharged from the hospital. Such effects may be seen with exposure to heroin. More socially accepted drugs, such as nicotine and alcohol, have profound effects on the growth of the fetus with subsequent effects on later health. 77,83 A pattern emerges such that certain exposures may adversely affect the neurodevelopment and health of the exposed fetus and newborn infant for years to come. This article reviews the placental-maternal circulation and the transfer of drugs to the fetus, the critical periods of drug exposure during fetal development, and how such effects may be manifested in the newborn period. Topics include specific recreational drugs and their effects on the fetus and neonate, indications for screening, potential therapies for drug withdrawal, and parameters for long-term neurodevelopmental and psychosocial assessment of the infant and child.