What is the appropriate management of asthma in a pregnant patient?

Management of Asthma in Pregnancy

Continue all asthma medications during pregnancy without reduction or discontinuation, as uncontrolled asthma poses far greater risks to both mother and fetus than any medication used to treat it. 1

Core Principle: Active Management is Essential

Uncontrolled maternal asthma directly threatens both maternal and fetal outcomes through multiple mechanisms. Poor asthma control increases risks of perinatal mortality, preeclampsia, preterm birth (46% increased risk of low birthweight), intrauterine growth restriction, gestational diabetes, and cesarean section. 2 Active asthma management during pregnancy demonstrably reduces these risks, including preterm birth, neonatal hospitalization, and gestational diabetes. 2

The fundamental error clinicians make is reducing or withholding asthma medications due to pregnancy concerns—this causes fetal hypoxia, which is far more harmful than medication exposure. 1

Stepwise Pharmacologic Management

Quick-Relief Medication (All Patients)

Albuterol is the preferred short-acting beta-agonist due to the most extensive pregnancy safety data (6,667 pregnant women studied, including 1,929 with asthma). 2, 1

• Dosing: 2-4 puffs via MDI every 20 minutes for 3 doses as needed, then every 1-4 hours 2, 1
• Alternative: 2.5 mg via nebulizer every 20 minutes for 3 doses, then every 1-4 hours 1, 3
• Use exceeding 2 times weekly (or daily use in persistent asthma) indicates need to initiate or intensify controller therapy 2

Controller Medication (Persistent Asthma)

Inhaled corticosteroids are the preferred maintenance therapy for all levels of persistent asthma. 1

Budesonide is the first-choice inhaled corticosteroid because it has the most extensive pregnancy safety data, with studies of 2,534 infants showing no increased risk of congenital malformations (3.6% vs 3.5% general population rate). 2, 1, 4

• Low dose: 200-600 mcg daily 5
• Studies demonstrate relative safety regarding congenital malformations, with no association between maintenance ICS use and increased malformation risk 2
• The small increased risk of congenital malformations in women with asthma (RR 1.11) is not associated with ICS use but rather with the disease itself 2

Add-On Therapy for Inadequate Control

Theophylline is safe at recommended doses (serum concentration 5-12 mcg/mL) during pregnancy, though side effects and discontinuation rates are higher than with ICS. 2

Management of Acute Exacerbations

Treat exacerbations aggressively—inadequate control poses greater risk than the medications. 1, 3

Initial Treatment

• Albuterol: 2.5 mg via nebulizer every 20 minutes for 3 doses, then every 1-4 hours as needed 1, 3
• For severe exacerbations: Add ipratropium bromide 0.5 mg (combined with albuterol 2.5 mg) every 20 minutes for 3 doses, then every 2-4 hours 1, 3

Systemic Corticosteroids

When exacerbations are not quickly controlled with bronchodilators:

• Outpatient: Prednisone 40-60 mg daily for 3-10 days 3
• Severe/inpatient: Prednisone 120-180 mg/day in 3-4 divided doses for 48 hours, then 60-80 mg/day until peak expiratory flow reaches 70% of predicted 3
• Oral prednisone is as effective as IV corticosteroids when GI absorption is intact 3

Important caveat: Oral corticosteroid use is associated with increased incidence of preeclampsia, preterm delivery, and low birthweight infants, though it remains difficult to separate medication effects from effects of severe uncontrolled asthma itself. 2

Monitoring Strategy

Monthly monitoring of symptoms and pulmonary function throughout pregnancy is essential due to the unpredictable course of asthma during gestation. 2 This should involve both obstetric care providers and a multidisciplinary respiratory team. 2

Pattern Recognition During Pregnancy

• First trimester and last month: relatively free of exacerbations 2
• Second and third trimesters: increased symptoms and medication needs are common 2
• Overweight/obese women: twice the frequency of exacerbations compared to healthy weight women 2

Fetal Surveillance

For moderate-to-severe or suboptimally controlled asthma: Serial ultrasounds starting at 32 weeks gestation to assess fetal growth. 1, 3 This is particularly important following moderate-to-severe exacerbations, which increase risk of intrauterine growth restriction. 2

Management of Comorbidities and Risk Factors

Control of triggers and comorbidities is recommended and includes: 2

• Rhinitis: Common indicator of atopy associated with worsening asthma during pregnancy 2
• Obesity: Requires particular attention given doubled exacerbation risk 2
• Influenza vaccination: Recommended for all pregnant women with asthma 2
• Smoking cessation: Essential intervention 2
• Sleep-disordered breathing and snoring: Should be addressed 2

Adjunctive Interventions

Self-Management Education

Asthma self-management education improves skills and knowledge in pregnant women with asthma. 2

Exercise and Nutrition

• Maternal exercise: Beneficial for reducing low fetal birthweight, particularly important for overweight/obese women 2, 1
• Vitamin D: Most pregnant women with asthma have levels <75 nmol/L, associated with greater risk of adverse respiratory outcomes and childhood asthma in offspring 2, 1

Advanced Monitoring

Exhaled nitric oxide fraction-guided management reduces asthma exacerbations, neonatal hospitalization, infant bronchiolitis, and later development of childhood wheeze and asthma. 2

Common Pitfalls to Avoid

1. Never reduce or discontinue asthma medications due to pregnancy concerns—uncontrolled asthma causes fetal hypoxia, which is far more harmful than medication exposure 1, 3

2. Do not withhold systemic corticosteroids during severe exacerbations—the risks of uncontrolled severe asthma exceed any medication risks 2, 3

3. Avoid assuming "one-third improve, one-third unchanged, one-third worsen" applies to individual patients—this requires monthly monitoring as the course is unpredictable 2

4. Do not use oral decongestants in early pregnancy due to potential association with rare birth defects 3

5. Maintain arterial oxygen saturation above 95% during exacerbations for fetal well-being 3