Xolair and Pregnancy – May Not Be Recommended

David Fuller

Last Updated On: October 6, 2025

Asthma is one of the most common chronic conditions affecting women of childbearing age, and pregnancy can often make symptom management more challenging. In fact, up to one-third of pregnant women with asthma experience flare-ups or worsening symptoms, which may impact both maternal health and fetal development. This makes careful, individualized treatment decisions critical during pregnancy.

Xolair (omalizumab), a biologic therapy approved for moderate to severe allergic asthma and chronic spontaneous urticaria, has helped many patients control difficult-to-manage symptoms. However, when it comes to pregnancy, the picture is less clear. Current data are limited, and because safety has not been firmly established, its use is generally not recommended unless the potential benefits outweigh the risks.

In this article, we will take a closer look at what is currently known about Xolair and pregnancy, examining registry data, available studies, and professional guidelines, to help both patients and clinicians navigate this complex and vital decision.

Key Takeaways

• Evidence on Xolair in pregnancy is limited, but registry and observational data so far have not shown an increased risk of birth defects.
• The EXPECT registry findings are reassuring, though ongoing monitoring is still important.
• Uncontrolled asthma poses greater risks to both mother and baby than treatment with Xolair in many cases.
• There are theoretical concerns about infant immunity due to placental transfer, but no confirmed long-term effects have been reported.
• Breastfeeding appears generally safe, as only small amounts pass into breast milk and no harm has been reported in infants.
• Initiating Xolair in pregnancy is not usually recommended, but continuing therapy may be appropriate if stopping would worsen maternal health.
• Shared decision-making and close monitoring with specialists are key to ensuring safety for both mother and child.

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Clinical Data on Xolair Safety During Pregnancy and Lactation

Research on Xolair (omalizumab) use in pregnancy is more limited than for many other medications, largely because controlled trials in pregnant women are not ethically feasible. Instead, clinicians rely on observational data and registry reports. So far, these studies suggest no clear evidence of birth defects (congenital anomalies) directly linked to Xolair, but uncertainties remain.

When considering treatment, providers weigh the risks of the drug against the dangers of uncontrolled asthma, which is known to increase complications such as preterm birth, low birth weight, and maternal hospitalizations. In many cases, the health risks of poorly controlled asthma may be greater than the potential risks of continuing Xolair.

For breastfeeding, small amounts of omalizumab have been detected in breast milk, but current case reports suggest no harmful effects in breastfed infants. Because data are still limited, providers take a cautious approach—balancing the mother’s need for asthma or urticaria control with the potential for infant exposure.

EXPECT Registry and Real-World Evidence for Omalizumab in Pregnancy

To fill gaps in evidence, the Xolair EXPECT registry was established to systematically track pregnancy outcomes in women exposed to omalizumab. Since clinical trials in pregnant populations are not feasible, this registry plays a critical role in guiding real-world care.

Key Findings

• Rates of congenital anomalies in infants exposed to Xolair were not higher than in the general population, suggesting no major safety signal.
  
• Some cases of preterm birth and low infant birth weight were reported, but these outcomes are also strongly linked to maternal asthma severity itself, making causation difficult to prove.
  
• Women who maintained good asthma control with Xolair often experienced fewer flare-ups, fewer emergency visits, and overall healthier pregnancies.

While the findings are encouraging, limitations include reporting bias, relatively small sample sizes, and limited long-term follow-up for children exposed in utero. Despite these challenges, EXPECT remains the most comprehensive source of safety data on Xolair use in pregnancy and heavily informs clinical guidance worldwide.

Potential Risks of Xolair: Fetal Immune Effects and Placental Transfer

Like other monoclonal antibodies, Xolair can cross the placenta, particularly in later trimesters. This raises theoretical concerns about possible effects on the developing immune system.

Possible Risks

• Changes in neonatal immune responses.
  
• Increased vulnerability to infections in infancy.
  
• Possible influence on how infants respond to vaccines.

These risks remain theoretical. To date, no clinical evidence has shown that infants exposed to Xolair in utero experience long-term immune problems. Findings from registries and follow-ups remain reassuring, but ongoing monitoring continues.

Clinical Guidance: Weighing Maternal Benefits Against Potential Risks with Xolair

Guidelines recommend that Xolair should not be routinely started during pregnancy, but it may be continued if a woman is already on therapy and the benefits outweigh the risks of stopping. The decision is highly individualized.

Xolair’s Maternal Benefits

• Better asthma control: Reduces the chance of severe exacerbations, which are far riskier to both mother and baby than Xolair itself.
  
• Improved quality of life: Helps avoid emergency interventions and reliance on high-dose steroids, which may carry more pregnancy-related risks.
  
• Protection from maternal hypoxia: Stable asthma management lowers the risk of oxygen deprivation, which can directly affect fetal development.

For women who become pregnant while on Xolair, stopping therapy may cause worsening disease, which could create new risks. In many such cases, continuing treatment is considered the safer path.

Consulting a specialist and reviewing prescribing information from the Xolair manufacturer helps providers make well-informed, individualized decisions. This approach balances the mother’s health needs with the baby’s safety, supported by the best evidence available.

Conclusion

Xolair has proven value in managing severe allergic asthma and chronic urticaria, but its use during pregnancy and breastfeeding requires careful consideration. Data from the EXPECT registry and other real-world sources indicate no significant increase in birth defects. However, questions remain about the long-term effects on the immune system.

Ultimately, treatment decisions should rely on shared decision-making—weighing maternal disease control against potential risks. With close monitoring, specialist input, and adherence to updated guidance, Xolair can sometimes remain an option for pregnant patients when the benefits clearly outweigh the uncertainties.

FAQs

1. Is Xolair safe to use during pregnancy?

Current data suggest no major risk of birth defects, but uncertainties remain. It is typically considered only if the benefits to the mother outweigh the potential risks.

2. Can I continue Xolair while breastfeeding?

Small amounts pass into breast milk. However, case reports to date have shown no harmful effects in infants. Providers weigh risks and monitor closely.

3. What is the Xolair EXPECT registry?

A registry that tracks pregnancy outcomes in women exposed to Xolair. Results so far are reassuring but highlight the need for ongoing monitoring.

4. Should I stop Xolair if I become pregnant?

Not always. Stopping may worsen asthma or urticaria. Clinicians often continue therapy if maternal disease control is critical, with individualized guidance.

References

Genentech USA, Inc. Xolair (omalizumab) prescribing information. Revised March 2021. Accessed September 28, 2025. https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/103976s5238lbl.pdf

Namazy J, Cabana MD, Scheuerle AE, et al. Xolair Pregnancy Registry: outcomes in pregnant women with asthma. J Allergy Clin Immunol Pract. 2020;8(6):1902–1909.e3 https://doi.org/10.1016/j.jaip.2020.01.033