Effect of Maternal Asthma Exacerbations on Perinatal Outcomes: a Population-based Study

Background: Although there is a growing body of literature about the impact of asthma exacerbations during pregnancy on adverse perinatal outcomes, it is still unclear whether asthma exacerbations themselves or asthma severity are the driving factor for negative outcomes. This study aimed to estimate the associations between maternal asthma exacerbations and perinatal outcomes, and whether this differed by asthma treatment regime as a proxy for severity.

Methods: We included births of women with asthma in Sweden from July 2006 to November 2013 (n=33 829). Asthma exacerbations were defined as unplanned emergency visits/hospitalisations or a short course of oral corticosteroids. Adjusted odds ratios (aOR) were estimated for the associations between exacerbations during pregnancy and perinatal outcomes (small for gestational age (SGA), preterm birth, birthweight and mode of delivery), stratified by preconception treatment regime.

Results: Exacerbations occurred in 1430 (4.2%) pregnancies. Exacerbations were associated with reduced birthweight (aOR 1.45, 95% CI 1.24-1.70), and elective (aOR 1.50, 95% CI 1.25-1.79) and emergency caesarean section (aOR 1.35, 95% CI 1.13-1.61). Multiple exacerbations were associated with a 2.6-fold increased odds of SGA (95% CI 1.38-4.82). Amongst women treated prepregnancy with combination therapy (proxy for moderate-severe asthma), exacerbators were at increased odds of elective (aOR 1.69, 95% CI 1.30-2.2) and emergency (aOR 1.62, 95% CI 1.26-2.08) caesarean section, and SGA (aOR 1.74, 95% CI 1.18-2.57) non-exacerbators.

Conclusion: Maternal asthma exacerbations increase the risk of SGA and caesarean sections, particularly in women with multiple exacerbations or moderate-severe asthma. Adequate antenatal asthma care is needed to reduce exacerbations and reduce risks of poor outcomes.