At what gestational age should Valtrex (valacyclovir) be started in pregnant women with a history of genital herpes?

Valacyclovir Therapy in Pregnancy for Genital Herpes

Valacyclovir suppressive therapy should be started at 36 weeks' gestation in pregnant women with a history of genital herpes to reduce viral shedding, recurrences, and cesarean deliveries. 1

Timing of Valacyclovir Initiation

The timing of valacyclovir initiation depends on the clinical scenario:

1. For suppressive therapy in women with history of recurrent genital herpes:

   • Start at 36 weeks' gestation and continue until delivery 1, 2, 3
   • This timing has been shown to significantly reduce:
     • Clinical HSV recurrences (10.5% vs 27.3% with placebo) 2
     • Need for cesarean deliveries due to active lesions (4% vs 13% with placebo) 3
     • HSV viral shedding at delivery 2, 3

2. For treatment of active episodes during pregnancy:

   • Initiate treatment immediately when symptoms appear
   • For first episodes: 5-10 days of therapy 4
   • For recurrent episodes: 5-10 days of therapy 5

Dosing Recommendations

• Suppressive therapy (starting at 36 weeks):

  • Valacyclovir 500 mg twice daily 1, 5
  • Alternative: Acyclovir 400 mg three times daily 1

• Treatment of active episodes:

  • First episode: Valacyclovir 1000 mg twice daily for 5-10 days 4
  • Recurrent episode: Valacyclovir 500 mg twice daily for 5-10 days 5

Clinical Considerations

Efficacy of Suppressive Therapy

Randomized controlled trials have demonstrated that valacyclovir suppression starting at 36 weeks significantly:

• Reduces clinical recurrences by 60% (RR 0.4,95% CI 0.2-0.9) 2
• Decreases cesarean deliveries due to active herpes by approximately 70% 3
• Lowers HSV detection at delivery 2, 3

Safety Profile

• Valacyclovir appears to be safe during pregnancy 1
• No increased risk for major birth defects compared to the general population 1
• No significant differences in maternal, obstetric, or neonatal complications have been observed in clinical trials 2, 3

Special Scenarios

First episode during pregnancy:

• Treat the acute episode immediately
• Then initiate suppressive therapy at 36 weeks 4
• Cesarean delivery is recommended if first episode occurred less than 6 weeks before delivery 4

Recurrent episodes:

• Treat acute symptoms if bothersome
• Initiate suppressive therapy at 36 weeks regardless of recurrences during the current pregnancy 1, 5

Management at Delivery

• All women should be examined at the onset of labor for symptoms of genital herpes 1
• Cesarean delivery is recommended for women with active genital lesions or prodromal symptoms at the onset of labor 1
• In women on suppressive therapy without active lesions, vaginal delivery is appropriate 1

Common Pitfalls to Avoid

1. Delaying initiation of suppressive therapy beyond 36 weeks

   • Starting too late may not provide adequate protection against recurrence at delivery

2. Failing to distinguish between first episode and recurrent herpes

   • First episodes carry significantly higher risk of neonatal transmission (25-44%) compared to recurrences (approximately 1%) 6
   • Management differs substantially between these scenarios

3. Overlooking the need for cesarean delivery with active lesions

   • Despite suppressive therapy, cesarean delivery is still indicated if active lesions are present at the time of labor 1

4. Not considering HIV status

   • HSV increases the risk of perinatal HIV transmission 1
   • HIV testing should be performed in women with first episode genital herpes 4

By following these evidence-based guidelines, clinicians can significantly reduce the risk of HSV recurrence at delivery and the associated need for cesarean delivery, while maintaining maternal and neonatal safety.