Prior studies have found an increased incidence of adverse perinatal outcomes of pregnancies in asthmatic mothers, but these studies have been poorly controlled for asthma therapy and other confounding factors. The purpose of this study was to assess perinatal outcomes in actively managed pregnant asthmatic women as compared with matched nonasthmatic controls. Using an inception cohort design, we studied a volunteer sample of 486 pregnant (< 28 wk) women with documented asthma and 486 pregnant nonasthmatic controls with normal pulmonary function. Cases and controls were matched for age, smoking status, parity, and year of delivery. Asthma was managed with step therapy to prevent acute asthmatic episodes and asthma symptoms that interfered with sleep or normal activity. Chronic hypertension was significantly more common (p = 0.007) in asthmatic subjects (3.7%) than in matched controls (1.0%). However, no significant differences in incidences of preeclampsia, perinatal mortality, preterm births, low-birth-weight infants, intrauterine growth retardation, or congenital malformations were observed in the pregnancies of the asthmatic women as compared with the matched controls. Trends were observed toward relationships between more severe asthma requiring emergency therapy or corticosteroids and increased incidences of preeclampsia and low-birth-weight infants, but these associations were not statistically significant. These data suggest that the overall perinatal prognosis for women with actively managed asthma during pregnancy is comparable to that for the nonasthmatic population.