Maternal asthma medication use during pregnancy and risk of congenital heart defects

Asthma affects 4% to 8% of pregnant women and studies suggest maternal asthma, particularly when uncontrolled, may be associated with adverse reproductive outcomes.

We examined self-reported asthma medication use and the risk of congenital heart defects (CHD) in the National Birth Defects Prevention Study, a multi-center, population-based case-control study of selected major structural defects. We evaluated maternal use of bronchodilators and anti-inflammatories during the periconceptional period (1 month before conception through the first 3 pregnancy months) among 7638 infants with CHDs and 8106 nonmalformed controls with estimated delivery dates from 1997 to 2007. We used logistic regression to estimate odds ratios and 95% confidence intervals for 20 types of CHDs.

Among asthma medications reported during the periconceptional period among controls, albuterol accounted for 85.1% of all bronchodilator use, and fluticasone, prednisone, and montelukast accounted for 46.1%, 15.6%, and 14.9% of anti-inflammatory use, respectively. Of the women who reported bronchodilators during the periconceptional period, 71.1% reported use throughout pregnancy and only 29.4% reported concurrent use of an anti-inflammatory. We observed one statistically significant association between maternal bronchodilator use only and anomalous pulmonary venous return (odds ratio 2.3, 95% confidence interval 1.1-4.8) among numerous comparisons.

We did not observe statistically significant associations between the reported use of asthma medications during pregnancy and most specific types of CHDs. Despite limitations in our inability to evaluate asthma status and severity, our study suggests that maternal asthma medication use does not substantially, if at all, increase the risk of CHDs.