At 37 weeks and 3 days gestation with varicella exposure but no rash, how should I be managed?

Management at 37 Weeks + 3 Days Gestation Following Varicella Exposure Without Rash

At 37+3 weeks gestation with varicella exposure but no rash development, you should monitor closely for 28 days post-exposure (if VZIG was given) or 21 days (if no VZIG), and if a rash develops, immediately initiate oral acyclovir 800 mg five times daily within 24 hours of rash onset to prevent severe maternal complications, particularly pneumonia. 1

Immediate Assessment

• Confirm your varicella immunity status immediately through serology if not already documented. 1, 2
• If you are seronegative and the exposure occurred within the past 96 hours, you should have received varicella-zoster immune globulin (VZIG) to prevent severe maternal disease. 1, 2
• If VZIG was not administered and you are beyond the 96-hour window, the effectiveness of post-exposure prophylaxis is significantly diminished. 1, 3

Current Management Strategy

Monitoring Protocol

• Observe yourself closely for any signs or symptoms of varicella for 21 days after exposure (or 28 days if you received VZIG, as it prolongs the incubation period). 1
• Watch specifically for: prodromal symptoms (fever, malaise, headache) followed by the characteristic vesicular rash that starts on the head and trunk. 4

If Rash Develops

• Begin oral acyclovir 800 mg five times daily immediately—ideally within 24 hours of rash onset—to reduce severity of maternal symptoms and prevent complications like pneumonia. 1, 2
• Acyclovir is FDA Category B in pregnancy with strong safety data from 596 first-trimester exposures showing no increased birth defect rate. 1
• Seek immediate medical evaluation if you develop respiratory symptoms (cough, shortness of breath, chest pain), as varicella pneumonitis is life-threatening and requires hospitalization with intravenous acyclovir 10-15 mg/kg every 8 hours. 2, 3

Critical Peripartum Considerations

At 37+3 weeks, you are approaching the highest-risk period for neonatal varicella, which occurs when maternal rash appears between 5 days before delivery and 2 days after delivery. 1, 2

Neonatal Protection Plan

• If you develop varicella rash within 5 days before or 2 days after delivery, your newborn must receive VZIG immediately after birth, regardless of whether you received VZIG during pregnancy. 1, 2
• This timing creates the highest risk for severe neonatal disease and mortality because the infant is exposed to high viral loads without adequate maternal antibody protection. 1, 3
• Alert your obstetric team and neonatal providers immediately if rash develops, so they can prepare for appropriate neonatal prophylaxis. 2

Fetal Risk Assessment

• At this late gestational age (third trimester), there is no risk of congenital varicella syndrome, which only occurs with maternal infection before 20 weeks gestation. 5
• The primary concerns are maternal pneumonia and severe neonatal varicella if delivery occurs during the critical peripartum window. 1, 3

Common Pitfalls to Avoid

• Do not delay acyclovir treatment if rash develops—effectiveness is highest when started within 24 hours of rash onset. 1
• Do not assume VZIG prevents fetal infection or neonatal disease—its purpose is solely to prevent severe maternal complications; neonates still require their own VZIG if born during the critical peripartum window. 1
• Do not underestimate respiratory symptoms—pregnant women have significantly higher risk of varicella pneumonitis, which can be fatal without aggressive treatment. 2, 3

Delivery Timing Considerations

• If you remain asymptomatic throughout the monitoring period, proceed with routine obstetric care and delivery planning. 2
• If rash develops, consider delaying elective delivery (if medically safe) until you are no longer contagious (all lesions crusted over, typically 5-7 days after rash onset) to avoid the high-risk peripartum exposure window. 1, 2