Although some research has demonstrated that women with asthma may be at an increased risk for adverse outcomes during pregnancy, there may not be an increased risk for congenital malformations or pregnancy losses in these women, according to study findings published in The Journal of Allergy and Clinical Immunology: In Practice

This cohort study included 29,882 asthma-complicated pregnancies from the MarketScan database (2011-2015) and 160,638 from the Medicaid Analytic eXtract (MAX) database (2000-2014), both large US healthcare claims databases. Disease status was classified by disease severity (based on medications dispensed) and control (based on short-acting β-agonist prescriptions and exacerbations). The pregnancy loss cohort included stillbirth and spontaneous abortion outcomes, while the infant outcomes cohort included preterm birth, small-for-gestational-age (SGA), neonatal intensive care unit (NICU) admission, and congenital malformations. Relative risks (RRs) by disease status were estimated using log binomial models.

Asthma diagnosis, disease severity, and disease control were not associated with abortions, stillbirth, or congenital malformations. However, compared with women without asthma, women with asthma showed increased risks for preterm birth (pooled results of the 2 cohorts: RR, 1.09; 95% CI, 1.04-1.14), SGA (RR, 1.05; 95% CI, 0.98-1.13), and NICU admission (RR 1.14; 95% CI, 1.09-1.19) after adjustments.

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Women with poor late pregnancy asthma control showed a greater risk for preterm birth (MarketScan cohort: RR, 1.27; 95% CI, 1.06-1.53 and MAX cohort: RR, 1.40; 95% CI, 1.32-1.48) and NICU admission (MarketScan cohort: RR, 1.23; 95% CI, 1.01-1.49 and MAX cohort: RR, 1.26; 95% CI, 1.16-1.36) compared with women with well-controlled asthma. An association was identified between higher asthma severity and SGA (RR, 1.14; 95% CI, 0.94-1.38 and MAX cohort: RR, 1.19; 95% CI, 1.08-1.33).

Limitations to this study included potential underestimation of asthma in claims, the use of prescription records to estimate medication use, potential misclassification of outcomes, and a lack of important information on gestational age in prematurely terminated pregnancies.

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The researchers concluded that asthma exacerbations, rather than underlying disease severity, are associated with an increased risk for preterm delivery. They indicated that it is important for pregnant women with asthma of any severity to achieve asthma control to reduce the risk for complications. Furthermore, “the American College of Obstetricians and Gynecologists recommends the continued use of indicated medications throughout pregnancy.”

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.


Yland JJ, Bateman BT, Huybrechts KF, et al. Perinatal outcomes associated with maternal asthma and its severity and control during pregnancy [published online January 22, 2020]. J Allergy Clin Immunol Pract. doi:10.1016/j.jaip.2020.01.016