Physiological changes as a result of pregnancy can change a patient's presentation of asthma for the better or worse. To ensure the safety of the baby and mother, good control of asthma throughout pregnancy should be reinforced. Treatment with short-acting B2 agonists, inhaled corticosteroids, oral or intravenous theophylline and steroid tablets (when indicated for severe asthma) should be continued as normal. The only exceptions are leukotriene antagonists, which should only be continued where significant symptom improvement has been seen prior to pregnancy, which was not achieved by other drugs. During breastfeeding, all asthma medication should continue as normal.