The burden of asthma in pregnancy is increasing worldwide, with European estimates of at least 4% of women having asthma, and at least 8% of women in antenatal clinics in the United Kingdom having asthma.Increases in asthma prevalence have also been reported in the United States from around 3% to more than 8% since 1994. In Australia the prevalence of asthma in pregnancy is 12%. As the most common respiratory disorder to complicate pregnancy, asthma represents a significant public health issue. Adequate asthma treatment and careful management is the key to a successful pregnancy outcome for these mothers and babies.