OBJECTIVE:

To estimate the frequency of severe asthma exacerbations in pregnant women and to estimate whether there is an association with adverse perinatal outcomes.

METHODS:

Asthma exacerbations were evaluated in 146 women who were enrolled in a prospective cohort study of asthma and pregnancy. A severe exacerbation was defined as a hospital admission, emergency department presentation, or unscheduled doctor visit for asthma or a course of oral corticosteroids. Women were classified as having mild (n= 63), moderate (n= 34), or severe (n= 49) asthma.

RESULTS:

Severe exacerbations occurred in 8%(95% confidence interval [CI] 1.3–14.6%) of women with mild asthma, 47%(95% CI 30.3–63.8%) of women with moderate asthma, and 65%(95% CI 52–78.6%) of women with severe asthma at a mean gestational age of 25.1±0.9 (range 9–39) weeks of gestation. Among women who had severe exacerbations, there were 2 male stillbirths (P=. 102) and a significantly increased rate of male low birth weight (P=. 03). Maternal age, lung function, body mass index, gravidity, and parity were not different between women who did or those who did not have a severe exacerbation. Maternal pregnancy weight gain was significantly lower in women who had a severe exacerbation (P=. 039). Forty-three percent of severe exacerbations occurred in winter, 34% were associated with self-reported viral infection, and 29% with nonadherence to inhaled corticosteroid medication.

CONCLUSION:

The exacerbation rate among pregnant women with asthma is high and associated with poor outcomes for the male fetus. Improvements in asthma management to prevent severe exacerbations may lead to a better outcome for both mother and baby.

LEVEL OF EVIDENCE:

II-2

Severe asthma exacerbations occurred in 36 of pregnant women with asthma and were associated with an increased rate of low birth weight among male neonates.