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Asthma medication use and the risk of birth defects

Published online: July 31, 2020

Asthma and asthma medication use are common during pregnancy. Current clinical practice guidelines recommend women with asthma who become pregnant maintain their treatment as it is considered safer to be treated with asthma medication than to experience exacerbations during pregnancy. Yet, studies evaluating early pregnancy asthma medication use and the risk of specific birth defects have shown mixed results.

The Journal of Allergy and Clinical Immunology: In Practice published a study examining early pregnancy asthma medication use and the risk of 52 specific birth defects using data from the National Birth Defects Prevention Study, a case-control study in 10 US states that included pregnancies from 1997 through 2011. Howley and colleagues explored the risk of specific birth defects among women who reported asthma medication use compared to women who did not report asthma or asthma medication use. Asthma medication use was further analyzed by type of medication:  bronchodilator, anti-inflammatory, or both.

Of the 28,481 birth defect cases and 10,894 controls in the analysis, asthma medication was used by 4.6% of case mothers and 4.1% of control mothers. Use of only bronchodilators was associated with longitudinal limb deficiency, cleft palate, cleft lip, and truncus arteriosus. None of the birth defects were associated with use of only anti-inflammatory medications. Use of both medication types (which included combination products) was associated with biliary atresia and pulmonary atresia. The estimates of the association between use of only bronchodilator and longitudinal limb deficiency remained elevated in analyses partially controlled for asthma and asthma severity.   

The results of this study were reassuring in that most of the birth defects examined were not associated with asthma medication use. Yet, the findings suggest early pregnancy asthma medication, particularly bronchodilators, may moderately increase the risk of some specific birth defects, including longitudinal limb deficiency. Given that these specific birth defects are relatively rare, even with the observed odds ratios after exposure, the absolute risk is still small.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

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