What is the recommended management for a 20-year-old pregnant lady in her first trimester with no co-morbidities diagnosed with chicken pox (varicella)?

Management of Chickenpox in First Trimester Pregnancy

For a 20-year-old pregnant woman in her first trimester with chickenpox and no comorbidities, administer oral acyclovir 800 mg five times daily for 5-7 days, starting as soon as possible after rash onset, and provide detailed counseling about the low (<1%) but real risk of congenital varicella syndrome. 1, 2, 3

Immediate Antiviral Treatment

• Oral acyclovir (800 mg five times daily for 5-7 days) should be initiated immediately upon diagnosis, ideally within 24 hours of rash onset, to reduce maternal complications 1, 3
• Acyclovir is FDA Pregnancy Category B and has been extensively studied in pregnancy with no increased risk of birth defects documented in a registry of 749 first-trimester exposures 1
• The drug should be started even if more than 24 hours have passed since rash onset, as maternal benefit still exists 3
• Ensure adequate hydration during treatment to prevent renal complications 1

Maternal Monitoring for Complications

• Assess for signs of varicella pneumonitis, which is the most serious maternal complication: fever, cough, dyspnea, chest pain, or tachypnea 4, 3
• If pneumonitis develops or the patient shows signs of severe disease, immediate hospital admission is required with intravenous acyclovir (10-15 mg/kg every 8 hours) 3
• Pregnant women are at significantly higher risk for severe varicella complications compared to non-pregnant adults 4

Fetal Risk Counseling and Monitoring

• Counsel the patient that congenital varicella syndrome risk is <1% when maternal infection occurs in the first or second trimester 2, 3
• Congenital varicella syndrome manifestations include limb hypoplasia, skin scarring, eye abnormalities, and neurological defects 2
• Arrange detailed fetal ultrasound at 16-20 weeks gestation (or 5 weeks after maternal infection) to screen for structural abnormalities suggestive of congenital varicella syndrome 3
• Serial ultrasounds should continue throughout pregnancy to monitor fetal growth and development 3

Critical Timing Considerations

• First trimester infection carries the risk of congenital varicella syndrome, but this risk is very low 2
• The highest risk period for severe neonatal varicella is maternal infection occurring 5 days before to 2 days after delivery (not applicable to this first-trimester case) 5, 3
• Maternal herpes zoster (shingles) reactivation later in pregnancy does not cause fetal harm 2

Common Pitfalls to Avoid

• Do not delay acyclovir treatment while waiting for confirmatory testing or specialist consultation—clinical diagnosis is sufficient to start therapy 3
• Do not withhold acyclovir due to pregnancy concerns—the maternal benefits clearly outweigh theoretical fetal risks, especially given the extensive safety data 1, 3
• Do not provide false reassurance—while congenital varicella syndrome is rare, the patient must understand it can occur and requires ultrasound surveillance 2, 3
• Do not miss early signs of pneumonitis—pregnant women can deteriorate rapidly, and this complication can be life-threatening 4

Postpartum and Future Pregnancy Planning

• After delivery, administer varicella vaccination postpartum (two doses, 4-8 weeks apart) to prevent infection in future pregnancies 3
• Varicella vaccine is contraindicated during pregnancy but safe immediately postpartum, even while breastfeeding 6, 3