Subcutaneous Immunotherapy and Pregnancy

Can immunotherapy be started if a patient is pregnant or planning to become pregnant?

No. It is generally not recommended to start immunotherapy if a patient is pregnant or planning to become pregnant.

A systemic reaction occurring during pregnancy may produce severe fetal hypoxia or precipitate premature uterine contractions, therefore immunotherapy should not be initiated during pregnancy.

Pregnancy is not a true contraindication for immunotherapy, but by custom, immunotherapy is not initiated until after delivery.

Can immunotherapy be continued if the patient is on it and becomes pregnant?

Yes, immunotherapy can be continued at the maintenance dose. There should not be a dose escalation during pregnancy.

The immunotherapy dose should not be increased in a pregnant patient until after delivery.

What happens when the immunotherapy extract expires during pregnancy and a new vial has to be used?

When a new vial is used, there is generally a "step down" in the immunotherapy dose. Whether the allergist proceeds to "build up" to the previously used maintenance dose or stays at the lower dose is a matter of debate. Many allergists are more cautious and do not escalate the dose during pregnancy.

Summary


"Pregnancy. Summary Statement 71: Allergen immunotherapy can be continued but is usually not initiated in the pregnant patient." Source: Cox L et al: J Allergy Clin Immunol 2007;120:S25-85. It is customary to hold the dose of immunotherapy until the time of delivery.

Sublingual immunotherapy is safe during pregnancy, also safe when initiated for the first time in pregnancy (study) (Allergy, 2012).

References

Allergen Immunotherapy. AFP, 2004.
Allergy Immunotherapy for Primary Care Physicians. J . Stokes , T . Casale. The American Journal of Medicine , Volume 119 , Issue 10 , Pages 820 - 823 (2006). Link via MDConsult.
Position Statement on the Administration of Immunotherapy Outside of the Prescribing Allergist Facility. ACAAI.
Allergen injection immunotherapy. John M Weiner. MJA 2006; 185 (4): 234.
Use of Immunotherapy in a Primary Care Office. AFP, 1998.
Safe allergen immunotherapy. Postgrad Med, 1996.
Advances in upper airway diseases and allergen immunotherapy in 2007. Saltoun C, Avila PC. J Allergy Clin Immunol. 2008 Aug 9.
Sublingual Immunotherapy. Anthony J. Frew. NEJM, Volume 358:2259-2264, May 22, 2008.
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Comments from Twitter

Dr John Weiner @AllergyNet: Always wondered about this. Data shows as many SCIT reactions on maintenance as escalation. Many allergists here will stop SCIT