Maternal Asthma and Use of Antiasthmatic Drugs in Early Pregnancy and Congenital Malformations in the Offspring

Abstract

Objectives: To investigate the risk of congenital malformations in infants born of women who had used antiasthmatic drugs in early pregnancy. Methods: Data were obtained from the Swedish Medical Birth Register for 1996-2011. Information on drug use was based on midwife interviews towards the end of the first trimester. Presence of congenital malformations was ascertained from three national health registers. Risk estimates were made with Mantel-Haenszel odds ratios after adjustment for delivery year, maternal age, parity, smoking, and body mass index. Consideration was taken to concomitantly used drugs. Results: Among more than 1.5 million women who gave birth, 2.9% reported the use of antiasthmatics. These women had characteristics which distinguished them from other women who gave birth and they more often than these used other drugs than antiasthmatics. These differences seemed to affect malformation risk only little. The risk for a major malformation was slightly but significantly increased (odds ratio=1.09, 95% confidence interval 1.03-1.12), specifically this was seen for cardiovascular defects, median cleft palate, and pyloric stenosis. There was no specific association with specific drugs or drug groups, the highest risk estimate was seen for women who used only one drug and notably a short-acting adrenergic or used three or more antiasthmatic drug groups. Conclusion: The absolute risk for a congenital malformation in infants born of women using antiasthmatics is low and some evidence indicates that it is due to underlying asthma. A good control of asthma seems important and scare of teratogenicity of the common antiasthmatic drugs should not prevent adequate use.