Montelukast use in Pregnancy not linked to Increased Risk of Congenital Malformations: Study
Canada: Use of montelukast, alone or in combination with inhaled corticosteroids (ICS) and/or long-acting β2-agonists (LABA), during the first trimester in women with asthma was not linked to an increased risk of major congenital malformations in their offspring.
A large population-based cohort study published in the Journal of Allergy and Clinical Immunology offers reassuring evidence on the safety of commonly used asthma controller medications during early pregnancy. Led by Xue-Feng Jiao from CHU Sainte-Justine, the study addressed concerns about potential fetal risks, particularly with montelukast.
Given that asthma is common in women of reproductive age and requires consistent control during pregnancy, uncertainties around medication safety have posed challenges in clinical decision-making. To address this, the researchers examined the association between first-trimester exposure to five commonly used asthma controller regimens and the risk of major congenital malformations.
Using data from the AMerican PREGNANcy Mother-Child CohorT (AM-PREGNANT) from 2003 to 2021, the study analyzed singleton live births to mothers with asthma, with exposure defined by first-trimester prescription fills.
A total of 44,435 pregnancies were included. Outcomes were compared across five treatment groups—montelukast alone, inhaled corticosteroids (ICS) alone, ICS with long-acting β2-agonists (LABA), montelukast with ICS, and a triple combination of montelukast, ICS, and LABA—against those with no controller medication use.
The study led to the following findings:
- No increased risk of major congenital malformations was observed across any of the five asthma controller medication groups compared to the non-exposed group.
- This finding was consistent for both overall malformations and organ-specific defects analyzed in the study.
- A possible association was noted between the combination of montelukast and inhaled corticosteroids (ICS) and an increased risk of cleft palate and/or cleft lip.
- The number of such cases was very small, limiting the robustness and reliability of this observation.
- The authors advised cautious interpretation of this finding and highlighted the need for larger studies to confirm the potential association.
Overall, the study offers important reassurance for clinicians and patients regarding the use of asthma controller medications during early pregnancy. Effective asthma management is crucial for maternal and fetal health, and avoiding or discontinuing therapy due to safety concerns can pose its own risks.
The authors concluded that first-trimester exposure to commonly used asthma controller regimens does not appear to elevate the risk of major congenital malformations. However, they highlighted the need for additional research to better understand rare outcomes and confirm the observed association with specific drug combinations.
These findings support continued use of appropriate asthma therapies during pregnancy, helping balance disease control with fetal safety.
Reference:
Jiao, X., Leal, L. F., Ducharme, F. M., Tse, S. M., & Bérard, A. (2026). First-trimester asthma controller medication use and major congenital malformation risk in offspring of women with asthma: A nationwide population-based cohort study. Journal of Allergy and Clinical Immunology. https://doi.org/10.1016/j.jaci.2026.03.013
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