Safety of Valacyclovir During Pregnancy
Valacyclovir is safe to use during pregnancy, with no increased risk of major birth defects compared to the general population. 1
Evidence on Safety
The FDA label for valacyclovir provides the strongest evidence regarding its safety during pregnancy:
- Clinical data collected over several decades with valacyclovir and its metabolite, acyclovir, have not identified any drug-associated risk of major birth defects 1
- The Valacyclovir Pregnancy Registry documented outcomes of 111 infants exposed to valacyclovir during pregnancy, with no significant increase in birth defects 1
- The Acyclovir Registry (with 1,246 documented outcomes) similarly showed no increased risk 1
This safety profile is further supported by a large population-based cohort study of 837,795 live births in Denmark, which found no association between first-trimester exposure to acyclovir or valacyclovir and increased risk of major birth defects (adjusted POR 0.89; 95% CI, 0.65-1.22) 2.
Pharmacokinetics in Pregnancy
- Valacyclovir is well-tolerated during pregnancy 3
- It is converted to acyclovir in the body
- While acyclovir concentrates in amniotic fluid, there is no evidence of preferential fetal drug accumulation 3
Clinical Benefits During Pregnancy
Valacyclovir offers important benefits for pregnant women with herpes infections:
- Significantly reduces clinical HSV recurrences during pregnancy (10.5% vs 27.3% with placebo) 4
- When used as suppressive therapy after 36 weeks gestation, reduces HSV shedding and recurrent genital herpes requiring cesarean delivery (4% vs 13% with placebo) 5
Recommendations for Use
The CDC recognizes the value of antiviral therapy for herpes during pregnancy 6:
- Oral acyclovir/valacyclovir is recommended for first clinical episodes of genital herpes during pregnancy
- IV acyclovir is indicated for life-threatening maternal HSV infections
- Suppressive therapy near term can be considered to reduce the risk of cesarean delivery
Important Considerations
Disease risk vs. medication risk: Untreated herpes simplex during pregnancy poses significant risks to the fetus, including potential neonatal HSV infection 1
Timing considerations: Valacyclovir suppressive therapy is most commonly initiated at 36 weeks gestation when used to prevent recurrences at delivery 4, 5
Monitoring: Women receiving valacyclovir should still be examined for symptoms of genital herpes at delivery 6
Conclusion
Based on extensive safety data and clinical benefits, valacyclovir can be confidently recommended during pregnancy when clinically indicated for treatment or suppression of herpes infections. The medication's established safety profile and effectiveness in reducing complications make it a valuable option for pregnant women with herpes simplex virus infections.