Pregnancy, asthma and exacerbations: a population-based cohort.

BACKGROUND

Asthma exacerbations during pregnancy are associated with adverse maternal and perinatal outcomes. Identifying modifiable risk factors is essential for improving health outcomes. We aimed to describe exacerbation patterns during pregnancy and identify exacerbation risk factors, particularly modifiable risk factors such as inhaled corticosteroid use.

METHODS

This was a cohort study using UK primary care and hospital data (2004-2020) to identify pregnant women with asthma. Exacerbations were defined as a short course of oral corticosteroids, emergency department visit or unscheduled hospital admission. Multivariable logistic regression was used to assess associations between maternal characteristics and exacerbations (primary outcome) and inhaled corticosteroid use (secondary outcome).

RESULTS

Among 40 196 pregnant women with asthma, total exacerbations declined by ∼30% during pregnancy. However, exacerbations associated with hospital admission increased by 30-45% during the second and third trimesters, declining abruptly after delivery. Inhaled corticosteroid prescriptions were reduced in 31% of women during pregnancy. Decreased inhaled corticosteroid use was associated with suboptimal asthma control pre-pregnancy, age, ethnicity and smoking. The strongest exacerbation risk factors were a history of exacerbations (adjusted OR 4.09, 95% CI 3.81-4.39), reduced inhaled corticosteroid use during pregnancy (adjusted OR 2.29, 95% CI 2.12-2.47) and ≥4 prescriptions per year for inhaled corticosteroids plus another preventer before pregnancy (adjusted odds ratio 2.11, 95% CI 1.87-2.37). Additional risk factors included blood eosinophilia, smoking and obesity.

CONCLUSIONS

Despite fewer total exacerbations, exacerbations associated with a hospital admission increased during pregnancy. One third of women reduced inhaled corticosteroid use during pregnancy, yet this was the second largest exacerbation risk factor and is completely modifiable. Other major risk factors were type 2 inflammation and another modifiable risk factor, suboptimal asthma control pre-pregnancy.