Is Valtrex (valacyclovir) safe to use during pregnancy?

Valacyclovir Safety During Pregnancy

Valacyclovir is safe to use during pregnancy and does not increase the risk of major birth defects. According to the FDA drug label, clinical data collected over several decades with valacyclovir and its metabolite acyclovir in pregnant women have not identified any drug-associated risk of major birth defects 1.

Evidence Supporting Safety

The FDA label provides the strongest evidence for valacyclovir's safety profile during pregnancy:

• The Acyclovir and Valacyclovir Pregnancy Registries documented outcomes of over 1,300 pregnancies with exposure to these medications 1
• The occurrence of major birth defects during first-trimester exposure to valacyclovir was 4.5%, which is not significantly different from the background risk in the general population 1
• The estimated background risk of major birth defects in the general population is 2% to 4% 1

A large population-based cohort study of 837,795 live births further supports this safety profile:

• Among 1,804 pregnancies exposed to acyclovir, valacyclovir, or famciclovir in the first trimester, there was no increased risk of major birth defects (adjusted POR 0.89) 2
• Specifically for valacyclovir, the adjusted prevalence odds ratio was 1.21, which was not statistically significant 2

Clinical Applications

Valacyclovir is commonly used during pregnancy for:

1. Treatment of first clinical episode of genital herpes

   • Oral therapy is recommended by the CDC 3

2. Suppressive therapy to prevent recurrent genital herpes

   • Valacyclovir 500mg twice daily starting at 36 weeks gestation significantly reduces:
     • Clinical HSV recurrences (10.5% vs 27.3% with placebo) 4
     • Need for cesarean delivery due to active herpes lesions (4% vs 13% with placebo) 5
     • HSV shedding at delivery 5

3. Pharmacokinetics in pregnancy

   • Valacyclovir results in higher plasma acyclovir levels than acyclovir itself during pregnancy 6
   • No evidence of preferential fetal drug accumulation has been found 6

Important Considerations

• Disease risk: Untreated herpes simplex during pregnancy poses significant risks to the fetus, including potential neonatal HSV infection 1
• Timing: For suppression of recurrent genital herpes, valacyclovir is typically started at 36 weeks gestation 4, 5
• Dosing: The typical suppressive dose is 500mg twice daily 4, 5
• Breastfeeding: Valacyclovir use is not contraindicated during breastfeeding 7

Monitoring

• Women should be examined at delivery for signs of active herpes lesions
• If no clinical recurrence or prodromal symptoms are present, vaginal delivery is permitted 5

In conclusion, valacyclovir is a safe option for pregnant women requiring herpes treatment or suppression, with substantial evidence supporting its use throughout pregnancy, including the first trimester.