The effect of pregnancy on asthma varies (see Asthma). Worsening of the disease is slightly more common than improvement, but most pregnant women do not have severe asthma attacks. The effect of asthma on pregnancy also varies. But if asthma is severe and poorly controlled, it increases the risk of preterm delivery and preeclampsia (a type of high blood pressure that occurs during pregnancy—see Preeclampsia and Eclampsia). Also, the fetus may not grow as much as expected, and cesarean delivery is more likely.
Because asthma can change during pregnancy, doctors may ask women with asthma to use a peak flow meter to monitor their breathing more often. Pregnant women with asthma should see their doctor regularly so that treatment can be adjusted as needed. Maintaining good control of asthma is important. Inadequate treatment can result in serious problems.
Inhaled bronchodilators (such as albuterol) and inhaled corticosteroids (such as budesonide) can be used during pregnancy. When inhaled, the drugs affect mainly the lungs and are less likely to affect the whole body and the fetus than when they are taken by mouth. Theophylline (taken by mouth) is not usually used during pregnancy. Corticosteroids taken by mouth are used only when other treatments are ineffective or after asthma suddenly worsens.
Being vaccinated against the influenza (flu) virus during the flu season is particularly important for pregnant women with asthma.
Last full review/revision September 2013 by Lara A. Friel, MD, PhD