What is the classification of asthma in pregnancy?

Classification of Asthma in Pregnancy

The classification of asthma in pregnancy follows the same framework as non-pregnant patients, with four categories: intermittent, persistent-mild, persistent-moderate, and persistent-severe, but requires more frequent monitoring due to the unpredictable course during pregnancy.

General Classification Framework

• Asthma severity in pregnancy is determined by assessing both impairment and risk domains, just as in non-pregnant patients 1
• The four classification categories are: intermittent, persistent-mild, persistent-moderate, and persistent-severe (note that "mild-intermittent" is no longer used as a classification) 1
• Classification should ideally be determined before initiating therapy to guide appropriate treatment selection 1

Components of Classification

Impairment Domain

• Daytime symptoms frequency (≤2 days/week for intermittent; >2 days/week but not daily for mild persistent; daily for moderate persistent; throughout the day for severe persistent) 1
• Nighttime awakenings (≤2 times/month for intermittent; 3-4 times/month for mild persistent; >once/week but not nightly for moderate persistent; often 7 times/week for severe persistent) 1
• Short-acting beta-agonist use for symptom control (≤2 days/week for intermittent; >2 days/week but not daily for mild persistent; daily for moderate persistent; several times/day for severe persistent) 1
• Interference with normal activity (none for intermittent; minor limitation for mild persistent; some limitation for moderate persistent; extremely limited for severe persistent) 1
• Lung function (normal FEV1 ≥80% predicted for intermittent; FEV1 ≥80% predicted for mild persistent; FEV1 >60% but <80% predicted for moderate persistent; FEV1 <60% predicted for severe persistent) 1

Risk Domain

• History of exacerbations requiring oral systemic corticosteroids is the primary marker of risk 1
• Final classification is determined by the most severe category in which any feature occurs 1

Special Considerations for Pregnancy

• Monthly monitoring of asthma symptoms and lung function is recommended throughout pregnancy due to the unpredictable course 1
• Approximately one-third of women experience improved asthma symptoms, one-third have unchanged symptoms, and one-third have worsened symptoms during pregnancy 1
• Asthma symptoms tend to be relatively stable during the first trimester and last month of pregnancy, with increased symptoms more common during the second and third trimesters 1
• Spirometry is the preferred method for objective assessment of lung function in pregnant women with suspected asthma, though peak expiratory flow (PEF) measurement is generally sufficient for routine follow-up 1, 2
• Serial ultrasound examinations starting at 32 weeks gestation may be considered for patients with suboptimally controlled asthma 1

Risk Factors for Worsening Asthma in Pregnancy

• Specific phenotypes like allergic or eosinophilic asthma are more likely to worsen during pregnancy 1
• Rhinitis as an indicator of atopy is associated with worsening asthma during pregnancy 1
• Overweight or obese pregnant women experience asthma exacerbations twice as frequently as healthy-weight pregnant women 1, 2
• Other risk factors include multiparity, Black race, exacerbations before pregnancy, and poor asthma control 3

Clinical Implications

• Uncontrolled asthma during pregnancy increases risks of pre-term birth, low birthweight, small for gestational age infants, pre-eclampsia, gestational diabetes, and perinatal mortality 1, 2
• Active asthma management during pregnancy reduces these risks 1
• Maintaining asthma control is critical for both maternal and fetal well-being, as it ensures adequate oxygen supply to the fetus 1
• Reduced quality of life is related to increased asthma severity and poor asthma control during pregnancy, underlining the importance of proper classification and management 4

Management Based on Classification

• Step 1 (Intermittent Asthma): Short-acting bronchodilators as needed, with albuterol being the preferred option due to its established safety profile in pregnancy 1
• Step 2 (Mild Persistent Asthma): Daily low-dose inhaled corticosteroid is the preferred treatment, with budesonide having the most safety data during pregnancy 1
• Higher steps follow similar principles as non-pregnant patients but require more vigilant monitoring and may need adjustment as pregnancy progresses 1