Asthma may be the most common potentialy serious medical problem to complicate pregnancy. Because severe uncontrolled asthma may cause both maternal and fetal morbidity and mortality, pharmacological asthma therapy is often necessary during pregnancy. Only 1 published randomized controlled clinical trial has evaluated the efficacy of an asthma medication (inhaled beclomethasone) during pregnancy. Human data bearing on the safety of medications during pregnancy are usually limited to observational studies, because experimental studies on the use of medications during human pregnancy would generally be unethical. Existing observational cohort data do not associate an increased risk of preeclampsia, total congenital malformations, preterm birth, or low birth weight infants with maternal exposures to inhaled beta agonists, theophylline, cromolyn, or inhaled corticosteroids. Maternal use of oral corticosteroids has been associated with reduced birth weight, an increased risk of preeclampsia, and an increased risk of oral clefts (first trimester use). Based on this information, benefit-risk considerations suggest that inhaled asthma medications and theophylline should be used when indicated for the treatment of asthma during pregnancy. Moreover, although some increased risks may be associated with the gestational use of oral corticosteroids, these risks are probably still less than the potential risks to the mother and the fetus of severe uncontrolled asthma. This articles describes recently published consensus recommendations regarding the pharmacological management of asthma during pregnancy.