What happens to pregnant women exposed to chickenpox (Varicella Zoster)?

Management of Pregnant Women Exposed to Chickenpox (Varicella Zoster)

Pregnant women without immunity to varicella zoster virus (VZV) who are exposed to chickenpox should receive varicella zoster immune globulin (VZIG) within 96 hours of exposure to prevent complications. 1

Risk Assessment and Immunity Status

• First step: Determine VZV immunity status through:

  • History of previous chickenpox infection
  • Documentation of varicella vaccination
  • VZV serology testing

• Pregnant women are considered susceptible/non-immune if they:

  • Have no history of chickenpox
  • Have not received varicella vaccine
  • Have negative or unknown VZV antibody status

Management Algorithm for Exposed Pregnant Women

For Non-Immune Pregnant Women:

1. Post-exposure prophylaxis:

   • Administer VZIG as soon as possible but within 96 hours of exposure 1
   • The infection rate in pregnant women given VZIG is approximately 30%, substantially lower than the expected rate of >70% in unimmunized exposed women 1

2. If VZIG is unavailable or exposure occurred >96 hours ago:

   • Consider oral acyclovir as an alternative prophylactic option 2
   • Recent evidence suggests oral acyclovir may be similarly effective to VZIG in preventing maternal chickenpox (30.8% vs 36.6% infection rates) 2

3. Monitoring after prophylaxis:

   • Observe closely for signs or symptoms of varicella for 28 days after exposure 1
   • Institute antiviral therapy immediately if signs or symptoms of varicella appear 1

For Immune Pregnant Women:

• No intervention needed as they are protected against new infection 3

Maternal and Fetal Risks

Maternal Risks:

• Pregnant women are at higher risk for severe varicella and complications including pneumonia 1
• The primary indication for VZIG in pregnant women is to prevent complications in the mother rather than to protect the fetus 1

Fetal/Neonatal Risks:

• Congenital varicella syndrome (limb hypoplasia, skin scarring, eye and neurological abnormalities) if infection occurs during first and second trimester 4
• Risk of congenital varicella syndrome is approximately 0.5-1.5% when infection occurs in first or second trimester 5
• Neonatal varicella is more severe if maternal rash appears 5 days before to 2 days after delivery 5

Special Considerations for Peripartum Exposure

• If maternal chickenpox develops from 5 days before to 2 days after delivery:

  • Administer VZIG to the neonate immediately after birth, regardless of whether the mother received VZIG 1
  • These neonates are at high risk for severe neonatal varicella 1, 5

• If maternal chickenpox develops >5 days before delivery:

  • VZIG is not necessary for the neonate as they should be protected by transplacentally acquired maternal antibody 1

Treatment of Active Infection in Pregnancy

• For mild disease: Supportive care
• For significant infection (e.g., pneumonitis):
  • Oral antiviral agents (acyclovir 800 mg 5 times daily) 4
  • Consider hospital admission for varicella pneumonitis 4
  • For severe complications, intravenous acyclovir (10-15 mg/kg every 8 hours for 5-10 days) 4

Prevention

• Varicella vaccination is recommended for all non-immune women as part of pre-pregnancy care 4
• Vaccination should not be administered during pregnancy 4
• Household contacts of susceptible pregnant women should be vaccinated if they have no history of chickenpox and are seronegative for HIV 3

Important Caveats

• VZIG administration does not prevent viremia, fetal infection, congenital varicella syndrome, or neonatal varicella 1
• Detailed ultrasound and appropriate follow-up is recommended for all women who develop varicella in pregnancy to screen for fetal consequences 4
• Neonatal healthcare providers should be informed of peripartum varicella exposure to optimize early neonatal care 4