Allergy Immunotherapy During Pregnancy
If you are already on maintenance-dose allergy shots, you can safely continue them during pregnancy, but you should not start allergy immunotherapy for the first time while pregnant. 1
Key Recommendations by Clinical Scenario
If Already on Maintenance Immunotherapy
- Continue your current maintenance dose safely - retrospective studies show no increased risk of prematurity, congenital malformations, hypertension/proteinuria, or perinatal deaths compared to the general population 1, 2
- Do not increase your dose during pregnancy, even if you were still in the build-up phase when you became pregnant 3, 1
- A large Swedish nationwide study of 743 pregnancies exposed to allergen immunotherapy found no association with congenital malformations (OR 0.90) or other adverse pregnancy outcomes 2
If Not Yet Started Immunotherapy
- Do not initiate allergy shots during pregnancy - this is a firm contraindication based on current guidelines 1
- The primary concern is the risk of systemic allergic reactions (anaphylaxis) and potential effects on the fetus from both the reaction itself and treatment with epinephrine, which could cause fetal hypoxia, spontaneous abortion, or premature labor 3
- While limited data from small numbers of women (7-31 patients across studies) who started immunotherapy during pregnancy showed no complications, this evidence is insufficient to establish safety 1
If in Build-Up Phase When Pregnancy Occurs
- Consider discontinuing immunotherapy if you are receiving doses unlikely to be therapeutic yet 3
- If continuing, maintain your current dose without escalation 1
The Exception: Life-Threatening Allergy
Initiation during pregnancy might be considered only when the clinical indication involves a high-risk medical condition, such as life-threatening anaphylaxis from insect sting (Hymenoptera) hypersensitivity 3
Safety Data Supporting Continuation
The evidence supporting continuation of established immunotherapy is reassuring:
- Retrospective studies of 121 pregnancies found no greater incidence of adverse outcomes than the general population 4
- Another study of 109 pregnancies receiving immunotherapy actually showed lower rates of abortion, prematurity, and toxemia compared to 60 pregnant patients who refused immunotherapy 5
- A prospective study of 185 pregnancies on sublingual immunotherapy showed complication rates lower than the general population 6
- Both subcutaneous (SCIT) and sublingual (SLIT) immunotherapy appear equally safe during pregnancy 2, 7
Important Precautions
- Enhanced monitoring is essential - the standard precautions for preventing adverse reactions are even more critical in pregnant patients due to potential fetal effects 3
- Discuss risks and benefits with your healthcare provider, as individual circumstances may vary 1
- Among the few pregnant women who experienced generalized reactions while receiving immunotherapy, none had fetal complications 7
What About Benefits to the Baby?
Some studies suggest potential benefits for offspring, including reduced allergic sensitization and lower allergen-specific IgE in cord blood, though more research is needed to confirm these findings 3