Seventy-five cocaine-using women enrolled in a comprehensive perinatal care program were divided into two groups: those who used cocaine in only the first trimester of pregnancy (group 1 [N = 23]) and those who used cocaine throughout pregnancy (group 2 [N = 52]). Perinatal outcomes of these pregnancies were compared with perinatal outcomes of a matched group of obstetric patients with no history or evidence of substance abuse (group 3 [N = 40]). Group 2 women had an increased rate of preterm delivery and low-birth-weight infants as well as an increased rate of intrauterine growth retardation. Group 1 women had rates of these complications similar to the drug-free group. Mean birth weight, length, and head circumference for term infants were reduced in only the group 2 infants. However, both groups of cocaine-exposed infants demonstrated significant impairment of orientation, motor, and state regulation behaviors on the Neonatal Behavioral Assessment Scale.