Montelukast Safety During Pregnancy
Montelukast can be safely used during pregnancy for recalcitrant asthma, especially in patients with prior favorable response, as it is classified as FDA Pregnancy Category B with no evidence of increased risk of major malformations. 1, 2
Safety Profile of Montelukast in Pregnancy
- Montelukast is classified as FDA Pregnancy Category B, indicating animal studies have not demonstrated risk to the fetus, but adequate controlled studies in pregnant women are limited 1, 2
- No teratogenicity was observed in animal studies at doses up to 100-110 times the maximum recommended human dose 2
- Montelukast crosses the placenta following oral dosing in rats and rabbits 2
- A prospective study of 180 montelukast-exposed pregnancies found no increased rate of major malformations above the baseline risk 3
- A more recent two-center cohort study in Japan confirmed that montelukast was not associated with increased risk of major congenital anomalies (adjusted odds ratio 0.78; 95% CI 0.23-2.05) 4
- A Danish population-based study found no significant increase in congenital anomalies with montelukast exposure (adjusted odds ratio 1.4; 95% CI 0.9-2.3) 5
Clinical Recommendations for Montelukast Use in Pregnancy
- Montelukast can be continued or initiated for recalcitrant asthma during pregnancy, particularly in patients who have shown favorable response prior to pregnancy 1
- The American Congress of Obstetricians and Gynecologists and the American College of Allergy support the use of montelukast in pregnancy when clinically indicated 1
- For asthma control, inhaled medications have been used for many years without documentation of adverse effects on the fetus, making them preferred first-line options 1
- The manufacturer maintains a registry for patients exposed to montelukast during pregnancy, and healthcare providers are encouraged to report prenatal exposures 2
Important Considerations and Potential Risks
- Birth weight may be slightly lower in infants exposed to montelukast during pregnancy, though this is likely associated with the severity of maternal asthma rather than the medication itself 3
- About 1% of montelukast passes into breast milk, but extensive metabolism and plasma protein binding are thought to limit infant exposure 1
- For nursing mothers, the benefits of breastfeeding generally outweigh the risk of exposure; consider breastfeeding prior to medication intake to further limit exposure 1
- While montelukast is considered safe for asthma treatment during pregnancy, it is generally not recommended for chronic rhinosinusitis (CRS) maintenance during pregnancy due to lack of efficacy data in this condition 1
Contraindications and Alternatives
- 5-lipoxygenase inhibitors (such as zileuton) should be avoided in both pregnant and lactating mothers 1
- For allergic rhinitis during pregnancy, intranasal corticosteroids (particularly budesonide, which is Pregnancy Category B) or sodium cromolyn may be preferred options 1
- If antihistamines are needed during pregnancy, those with established safety profiles (chlorphenamine, cetirizine, or loratadine) are preferred over newer agents 6
Monitoring Recommendations
- Regular monitoring of asthma control is essential during pregnancy, as poorly controlled asthma poses greater risks to maternal and fetal health than medication use 1
- Montelukast should be used at the lowest effective dose during pregnancy 1
- Healthcare providers should report prenatal exposure to montelukast to the manufacturer's pregnancy registry 2