Asthma in pregnancy

Definition

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

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

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

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