Asthma is one of the most common illnesses and the most common obstructive pulmonary disease encountered during pregnancy. Asthma may occur for the first time during pregnancy. Approximately one third of pregnant women with asthma improve, one third remain the same, and one third get worse. Regardless of their clinical status, pregnant women with asthma need effective pharmacologic and nonpharmacologic treatment to ensure their health and the health of their infants. Uncontrolled asthma can produce serious fetal and maternal complications; therefore aggressive management of the asthmatic pregnant patient is always indicated. Maternal complications in women with uncontrolled asthma include preeclampsia, gestational hypertension, hyperemesis gravidarum, vaginal hemorrhage, and preterm labor. Fetal complications include intrauterine growth retardation, preterm birth, low birth weight, increased perinatal mortality, and neonatal hypoxia.

Management of asthma is altered very little by pregnancy. As in the nonpregnant patient, effective management comprises four integral components: (1) objective measures for monitoring maternal lung function and fetal well-being; (2) avoidance and control of asthma triggers, including treating associated conditions such as sinusitis, rhinitis, and gastroesophageal reflux; (3) pharmacologic therapy; and (4) patient education.

Considerable experience with the use of methylxanthines during pregnancy has been accumulated. There has been no evidence of teratogenicity or fetal injury. The dosage does not usually need to be altered, but it is advisable to measure serum concentrations to ensure a therapeutic response and minimize side effects.

Adrenergic agents are effective bronchodilators used alone or in conjunction with methylxanthines. There has been extensive clinical experience with these drugs during pregnancy, with few reports of adverse effects. Administration of adrenergic medication by inhalation provides the most rapid relief of acute asthma with the fewest side effects. Older oral preparations containing phenobarbital should be avoided throughout pregnancy.

Cromolyn sodium prevents release of histamine and is useful for prophylaxis against acute asthma. It has no bronchodilating activity and is not useful for treatment of acute attacks. Cromolyn appears to have no maternal or fetal toxicity.

Acute bronchospasm unresponsive to bronchodilator therapy often improves with the antiinflammatory effect of corticosteroids. Oral, inhaled, and intravenous corticosteroids are all considered safe for use during pregnancy. Inhaled corticosteroids such as beclomethasone may allow a reduction in the dosage of oral preparations or the frequency of use of β-sympathomimetic inhalers.