What is the management of varicella (chickenpox) in a pregnant female?

Management of Varicella in Pregnancy

All non-immune pregnant women exposed to varicella should receive varicella-zoster immune globulin (VZIG) within 96 hours of exposure to prevent severe maternal complications, and if varicella develops, oral acyclovir 800 mg five times daily should be initiated within 24 hours of rash onset. 1, 2

Pre-Pregnancy and Initial Pregnancy Assessment

• Document varicella immunity status for all pregnant women through history of previous infection, vaccination records, or varicella-zoster IgG serology at the first prenatal visit. 3
• Counsel all non-immune pregnant women about the risks of varicella to themselves and their fetuses, instructing them to seek immediate medical attention following any exposure to chickenpox. 3
• Varicella vaccination is contraindicated during pregnancy but should be offered postpartum to all non-immune women. 3

Post-Exposure Prophylaxis

For Non-Immune Pregnant Women After Exposure

• Administer VZIG within 96 hours of exposure (ideally as soon as possible) to prevent severe maternal complications such as pneumonia. 1, 2, 3
• The primary purpose of VZIG is to prevent maternal complications—it does NOT prevent viremia, fetal infection, or congenital varicella syndrome. 1, 2
• VZIG may prolong the incubation period by more than one week, extending the monitoring period from 21 to 28 days after exposure. 2
• If serum immunity status is unknown and results cannot be obtained within 96 hours, administer VZIG empirically. 3
• If VZIG is unavailable or the exposure occurred more than 96 hours ago, consider oral acyclovir prophylaxis. 2, 4

Critical Timing Window

• The 96-hour window for VZIG administration is critical—effectiveness diminishes significantly after this timeframe. 2
• Failing to act within 96 hours is a major pitfall to avoid. 2

Treatment of Active Varicella Infection in Pregnancy

Antiviral Therapy

• For pregnant women who develop varicella, initiate oral acyclovir 800 mg five times daily within 24 hours of rash onset for maximum effectiveness. 2, 5, 3
• Treatment efficacy decreases significantly if started more than 24 hours after rash appearance. 2
• Acyclovir is FDA Category B in pregnancy, with a registry of 596 first-trimester exposures showing no increased rate of birth defects compared to the general population. 2, 5

Severe Complications

• For pregnant women with varicella pneumonitis or other severe complications, admit to hospital and administer intravenous acyclovir 10-15 mg/kg or 500 mg/m² every 8 hours for 5-10 days. 3, 6
• Pregnant women are at higher risk for severe varicella and complications, particularly pneumonia. 1, 2
• IV acyclovir should be considered for severe disease because oral formulations have poor bioavailability. 3

Fetal Monitoring and Counseling

Risk of Congenital Varicella Syndrome

• The risk of congenital varicella syndrome is approximately 0.4% during the first trimester and 2.0% during the second trimester (highest risk period). 7
• Risk decreases significantly after 20 weeks gestation. 7
• Counsel all pregnant women who develop varicella about the potential for congenital varicella syndrome and options for prenatal diagnosis. 3

Ultrasound Surveillance

• Perform detailed ultrasound with appropriate follow-up for all women who develop varicella in pregnancy to screen for fetal consequences of infection. 3

Peripartum Management (Critical High-Risk Period)

Maternal Infection Near Delivery

• The highest-risk period is when maternal varicella rash appears between 5 days before delivery and 2 days after delivery. 1, 8
• During this window, neonates lack sufficient transplacentally acquired maternal antibody, with historical mortality rates reaching 31% without intervention. 8

Neonatal Prophylaxis

• Administer VZIG to all neonates born to mothers with varicella onset from 5 days before to 2 days after delivery, regardless of whether the mother received VZIG. 1, 2, 8
• The recommended neonatal VZIG dose is 125 units per 10 kg body weight, maximum 625 units, administered as soon as possible after birth. 8
• Inform neonatal healthcare providers of peripartum varicella exposure to optimize early neonatal care. 3

If Neonatal Varicella Develops

• If varicella develops despite VZIG prophylaxis, initiate intravenous acyclovir immediately at 10 mg/kg IV every 8 hours for 10 days. 8
• Do not assume VZIG prevents infection—approximately 60% may still develop varicella, though severity and mortality are reduced. 8

Special Populations: Premature Infants with Postnatal Exposure

• Very premature infants (<28 weeks gestation or <1,000g) should receive VZIG regardless of maternal immunity status after postnatal exposure. 1, 8
• Moderately premature infants (≥28 weeks gestation) should receive VZIG only if the mother lacks evidence of immunity. 1, 8

Key Pitfalls to Avoid

• Do not delay VZIG administration beyond 96 hours after exposure in non-immune pregnant women. 2
• Do not withhold VZIG from neonates born during the critical 5-day-before to 2-day-after maternal rash window, even if the mother received VZIG. 8
• Do not delay acyclovir if varicella develops—start within 24 hours of rash onset. 2, 8
• Do not assume VZIG protects the fetus—its purpose is maternal protection only. 1, 2

Post-Exposure Monitoring

• Observe patients who receive VZIG closely for signs or symptoms of varicella for 28 days after exposure (extended from the usual 21 days due to VZIG's effect on incubation period). 1
• Institute antiviral therapy immediately if signs or symptoms of varicella develop. 1