Asthma in pregnancy

Definition

• Patients with asthma who become pregnant

Classification

• Mild intermittent
  • Symptoms <2 times per week ... ...
• Mild persistent
• Moderate persistent
  • Daily symptoms
  • Affect usual activities ...
• Severe
  • Continual symptoms
  • Nighttime symptoms
  • FEV1 <= 60% or predicted
  • Peak flow > 30% variability

Epidemiology

• 4-8% of pregnancies
• Most common chronic condition affecting pregnancy

Differential Diagnosis

• Chronic obstructive lung disease
• Pulmonary embolism
• Normal changes in pregnancy

Clinical Presentation

• Chest tightness, shortness of breath
• Triggers same as for asthma
  • Allergens
    • Pollen
    • Mold
    • Animals
    • Feathers
    • House dust mites
    • Cockroaches
  • Other environmental factors
  • Exercise
  • Infection
  • Stress

Investigations

• Spirometry
  • Reversible airway obstruction with FEV1 improving by at least 12% after bronchodilator
  • See article on Asthma for further criteria

Prognosis

• For the asthma, 1/3 of patients improve, 1/3 of patients worsen, and 1/3 of patients stay the same
  • Severe asthma is more likely to worsen
  • Changes in previous pregnancies is most predictive
  • Return to baseline within 3 months of delivery
  • Exacerbations more common during second half of pregnancy
• For the pregnancy, mild and well-controlled asthma has excellent outcomes
• For the pregnancy, severe or poorly-controlled can cause:
  • Hypertension
  • C section
  • Preeclapmsia
  • Stillbirth
  • Fetal growth restriction

Management

• Treatment is safer than untreated asthma
• Antenatal
  • Severe asthma
    • Respiratory exam
    • Peak flow measurement and spirometry
    • Review symptoms at every visit
  • All asthma
    • Influenza vaccination
    • Smoking cessation
• General asthma control with step therapy
  • Patient education, including trigger control or avoidance
  • SABA prn
    • Albuterol preferred
  • Low-dose inhaled corticosteroids
    • Budesonide preferred in pregnancy
  • Add LABA or medium-dose corticosteroids
  • Systemic corticosteroids for exacerbations
• Acute exacerbations
  • Humidified O2
  • Beta agonists
  • Corticosteroids
  • CXR
  • Pulse oximetry
  • Intubation
• During labour
  • Continue medication
  • Hydration and analgesia to reduce chance of bronchospasm
  • Hydrocortisone if needed
• Breastfeeding
  • Asthma medications not contraindicated