What is the management of an allergic reaction during pregnancy?

Management of Allergic Reactions During Pregnancy

Epinephrine remains the first-line treatment for anaphylaxis during pregnancy and should be administered immediately without hesitation, as the benefits of treating maternal anaphylaxis far outweigh any theoretical fetal risks. 1, 2

Anaphylaxis Management (Life-Threatening Reactions)

Immediate Actions

• Administer epinephrine 0.5 mg (1:1000 concentration) intramuscularly into the mid-outer thigh immediately, repeating every 5 minutes as needed to control symptoms and blood pressure 1
• Position the patient with left uterine displacement to prevent aortocaval compression—this is critical and unique to pregnancy management 3, 1
• Administer crystalloid fluids (normal saline) 20 mL/kg as rapid bolus, repeated as needed; large volumes up to 30 mL/kg in the first hour may be necessary 3, 1
• Provide high-flow supplemental oxygen to maintain maternal systolic blood pressure ≥90 mmHg for adequate placental perfusion 4

Graded Response by Severity

For Grade II (Moderate) reactions: Give epinephrine 20 mcg IV bolus initially, escalating to 50 mcg if inadequate response at 2 minutes, plus 500 mL crystalloid rapid bolus 1

For Grade III (Severe) reactions: Give epinephrine 50 mcg IV bolus (or 100 mcg if inadequate response to other vasopressors), plus 1 L crystalloid rapid bolus 1

Obstetric Considerations

• Consider emergent cesarean section early if persistent hypotension despite aggressive resuscitation 3, 1
• Initiate perimortem cesarean delivery if persistent hypotension after 4 minutes of cardiac arrest, with delivery of the fetus 1 minute later if usual resuscitation measures have not achieved return of spontaneous circulation 3, 1
• Continuous electronic fetal monitoring is essential throughout the episode 4

Post-Acute Management

• Observe all patients in a monitored area for minimum 6 hours from onset of reaction 3, 1
• Most patients with Grade III-IV reactions will require ICU admission 3, 1
• Prescribe epinephrine auto-injector with education on self-administration 1
• Refer to allergist-immunologist for comprehensive evaluation and allergy testing to identify specific triggers 1

Non-Anaphylactic Allergic Conditions

Allergic Rhinitis

Intranasal corticosteroids are first-line therapy due to superior efficacy and safety profile at recommended doses 3, 5

• Budesonide is the preferred intranasal corticosteroid during pregnancy 6
• Second-generation antihistamines: cetirizine or loratadine are the drugs of choice 3, 6
• First-generation antihistamines (chlorpheniramine) are acceptable based on longer safety data, though they cause more sedation 5
• Intranasal cromolyn is safe but less effective than corticosteroids 3, 5
• Montelukast (leukotriene receptor antagonist) can be used but has minimal pregnancy data 3, 6
• Avoid oral decongestants during first trimester due to conflicting reports of association with gastroschisis and small intestinal atresia 3

Asthma Management

• Continue inhaled corticosteroids; budesonide is the preferred agent 3, 6
• Manage exacerbations aggressively as they pose definite risk to mother and fetus 3
• For severe persistent asthma requiring additional therapy beyond medium-dose inhaled corticosteroids, increase to high-dose budesonide 3
• Systemic corticosteroids are warranted for severe uncontrolled asthma despite uncertain risks, as severe uncontrolled asthma poses definite risk 3

Medications to Avoid

Do not use intranasal antihistamines, mycophenolate mofetil, methotrexate, cyclosporine, azathioprine, or zileuton during pregnancy 6

Allergen Immunotherapy During Pregnancy

Continuation of Existing Therapy

• Women already on maintenance allergen immunotherapy can safely continue during pregnancy without dose increases 7, 8
• Maintain current dose; do not escalate 3, 7
• Retrospective studies show no increased risk of prematurity, congenital malformations, hypertension, or perinatal deaths 7
• Both subcutaneous (SCIT) and sublingual (SLIT) immunotherapy appear safe to continue 7

Initiation of New Therapy

• Do not initiate allergen immunotherapy during pregnancy, except in life-threatening cases of Hymenoptera (bee/wasp sting) anaphylaxis 3, 7, 8
• The concern is potential for systemic allergic reactions causing spontaneous abortion, premature labor, or fetal hypoxia 7

Safety Protocols

• Ensure full observation period after each injection 7
• Report any symptoms immediately 7
• Have injectable epinephrine immediately available 7

Critical Pitfalls to Avoid

The most dangerous error is delaying epinephrine administration in anaphylaxis—there is no contraindication to epinephrine use in pregnancy when treating anaphylaxis 1, 2

Failing to position patient with left uterine displacement worsens both maternal hypotension and fetal compromise 1

Do not restrict maternal diet during pregnancy as a strategy for preventing food allergy development in the infant 3