Drug abuse during pregnancy is associated with adverse perinatal outcome. Patterns of abuse have changed in recent years with the increasing popularity of cocaine. We compared pregnancy outcome data from 137 women receiving prenatal care in the Perinatal Center for Chemical Dependence of Northwestern Memorial Hospital with those of matched controls. Among drug-using women, the mean gestational age at delivery and mean birth weight were significantly lower than those of controls. In addition, study pregnancies were more frequently complicated by the need for antenatal hospitalization, preterm delivery, low birth weight (less than 2500 g), and abruptio placentae.