HSV Prophylaxis at 35 Weeks Gestation

Primary Recommendation

• The American College of Obstetricians and Gynecologists recommends initiating suppressive antiviral prophylaxis with oral acyclovir 400 mg three times daily (or valacyclovir 1000 mg twice daily) starting at 36 weeks and continuing until delivery for pregnant women at 35 weeks gestation with a history of genital herpes during pregnancy 1, 2

Clinical Decision Algorithm

• Women with documented genital herpes during current pregnancy should start suppressive therapy at 36 weeks gestation with acyclovir 400 mg orally three times daily OR valacyclovir 1000 mg orally twice daily 1, 2
• Some experts recommend prophylaxis for women with frequent, severe recurrences (BIII recommendation) 3, 4, 5

Safety Profile in Pregnancy

• The Centers for Disease Control and Prevention confirms that acyclovir and valacyclovir are safe for use in late pregnancy, with no increased risk of major birth defects compared to the general population 3, 4, 5

Dosing Regimens

• The preferred options for suppressive prophylaxis starting at 36 weeks are acyclovir 400 mg orally three times daily until delivery or valacyclovir 1000 mg orally twice daily until delivery 1, 2

Critical Context: Neonatal Transmission Risk

• Primary HSV infection near delivery carries a 30-50% neonatal transmission risk, while recurrent HSV at delivery carries a 1-3% neonatal transmission risk 1, 2

Management at Delivery (35 Weeks Context)

• Cesarean delivery is mandatory if visible genital lesions or prodromal symptoms are present at labor onset, regardless of whether this represents primary or recurrent disease 1, 2
• Cesarean delivery reduces transmission risk by approximately 85% when lesions are present 1

Common Pitfalls to Avoid

• The American College of Obstetricians and Gynecologists recommends not delaying prophylaxis beyond 36 weeks gestation, as the evidence base specifically supports initiation at 36 weeks 1
• Systemic oral therapy is required for suppression, and topical antivirals should not be used 4, 5

Neonatal Monitoring After Delivery

• All infants exposed to HSV during birth require careful clinical follow-up with surveillance cultures of mucosal surfaces 24-48 hours after birth, and should not be routinely treated with acyclovir unless symptomatic 1