Under the auspices of the National Asthma Education Program (NAEP), a Working Group on Asthma and Pregnancy developed a statement regarding the treatment of asthma during pregnancy. In its deliberations, the Working Group noted the paucity of data on the relative contributions of biological, social, and environmental factors on asthma in pregnant women, as well as the lack of data on the efficacy and safety of commonly used asthma therapies in pregnancy.