Short-acting inhaled beta2-agonists, often called "asthma relievers" or "rescue medications," are used as necessary to control acute symptoms. Albuterol is the preferred short-acting inhaled beta2-agonist for use during pregnancy since there are more available reassuring human gestational safety data.
Two long-acting inhaled beta agonist, salmeterol (Serevent®) and formoterol (Foradil®), are available. No large-scale trials of these medications in pregnancy have been performed. However, because of their inhaled route, chemical relation to albuterol, and efficacy data, long-acting beta agonists are recommended during pregnancy for patients not controlled on inhaled corticosteroids.
Theophylline has extensive human experience without evidence of significant abnormalities. Newborns can have jitteriness, vomiting and fast pulse if the maternal blood level is too high. Therefore, patients who receive theophylline should have blood levels checked during pregnancy.
Ipratropium (Atrovent®), an anticholinergic bronchodilator medication, does not cause problems in animals; however, there is no published experience in humans. Ipratropium is absorbed less than similar medications in this class, such as atropine.
The anti-inflammatory medications are preventive, or "asthma controllers," and include inhaled cromolyn (Intal®), corticosteroids and leukotriene modifiers. Patients requiring the use of beta2-agonists more often than three times a week, or who have reduced peak flow readings or spirometry (lung function studies), usually need daily anti-inflammatory medication. Inhaled cromolyn sodium is virtually devoid of side effects but is less effective than inhaled corticosteroids.
Budesonide (Pulmicort®) is recommended as the inhaled corticosteroid of choice for use during pregnancy due to a large amount of reassuring human gestational safety data. However, other inhaled corticosteroids (such as beclomethasone [Qvar®], fluticasone [Flovent®], flunisolide [Aerobid®], mometasome [Asmanex®], and triamcinolone [Azmacort®] have not been proven to be unsafe during pregnancy and can be continued in patients well-controlled by them prior to pregnancy.
In some cases oral or injectable corticosteroids, such as prednisone, prednisolone or methyprednisolone may be necessary for a few days in patients with severe asthma exacerbations or throughout pregnancy in women with severe asthma. . Some studies have demonstrated a slight increase in the incidence of pre-eclampsia, premature deliveries or low-birth-weight infants with chronic use of corticosteroids. However, they are the most effective drugs for the treatment of patients with more severe asthma and other allergic disorders. Therefore, their significant benefit usually far exceeds their minimal risk.
Three leukotriene modifiers, montelukast (Singulair®), zafirlukast (Accolate®), and zileuton (Zyflo®) are available. Results of animal studies are reassuring for montelukast and zafirlukast , but there are minimal data in human pregnancy with this new class of anti-inflammatory drugs.
For pregnant women with asthma, the type and frequency of fetal evaluation is based on gestational age and maternal risk factors. Ultrasound can be performed before 12 weeks if there is concern about the accuracy of an estimated due date and repeated later if a slowing of fetal growth is suspected. Electronic heart rate monitoring, called "non-stress testing" or "contraction stress testing," and ultrasonic determinations in the third trimester may be used to assess fetal well being. For third trimester patients with significant asthma symptoms, the frequency of fetal assessment should be increased if problems are suspected. Asthma patients should record fetal activity or kick counts daily to help monitor their baby according to their physician's instructions.
During a severe asthma attack in which symptoms do not quickly improve, there is risk for significant maternal hypoxemia, a low oxygen state. This is an important time for fetal assessment; continuous electronic fetal heart rate monitoring may be necessary along with measurements of the mother's lung function.
Fortunately during labor and delivery, the majority of asthma patients do well, although careful fetal monitoring remains very important. In low risk patients whose asthma is well-controlled, fetal assessment can be accomplished by 20 minutes of electronic monitoring (the admission test). Intensive fetal monitoring with careful observation is recommended for patients who enter labor and delivery with severe asthma, have a non-reassuring admission test, or other risk factors.