Acyclovir Safety in Pregnancy and Family Planning for HSV Infection
Safety Profile in Pregnancy
Acyclovir is safe to use during pregnancy for women with herpes simplex virus (HSV) infection, with no increased risk of major birth defects compared to the general population. 1, 2
- Current registry findings do not indicate an increased risk for major birth defects after acyclovir treatment compared to the general population 3
- Acyclovir crosses the placenta, with cord blood levels ranging from 0.5 to 3 μmol/L, which may be effective for in utero inhibition of viral replication 4
- The FDA classifies acyclovir as Pregnancy Category B, indicating that animal reproduction studies have not demonstrated fetal risk, but there are no adequate well-controlled studies in pregnant women 2
- A prospective registry of 749 pregnancies with first-trimester exposure to systemic acyclovir showed birth defect rates approximating those in the general population 2
Treatment Recommendations During Pregnancy
First Episode HSV Treatment
- Oral acyclovir 400 mg three times daily for 7-10 days is recommended for first episode genital herpes during pregnancy 1
- Valacyclovir 1 g orally twice daily for 7-10 days is an alternative option 1
- For life-threatening maternal HSV infection (e.g., disseminated infection, encephalitis, pneumonitis), intravenous acyclovir is indicated 3, 1
Recurrent HSV Management
- For patients with frequent or severe recurrences of genital HSV disease during pregnancy, acyclovir prophylaxis might be indicated 3
- Daily suppressive therapy with oral acyclovir or famciclovir is recommended for persons with frequent recurrences 3
- Valacyclovir is also considered an option for suppressive therapy 3
Prevention of Neonatal Herpes
- The risk of transmission to the neonate is high (30%-50%) among women who acquire genital herpes near the time of delivery 3
- The risk is low (≤3%) among women with a history of recurrent herpes at term 3, 1
- Acyclovir prophylaxis during late pregnancy may reduce the rate of cesarean deliveries by decreasing the incidence of active lesions, though routine administration is not universally recommended 3
- A cost-effectiveness analysis found that acyclovir prophylaxis at 36 weeks of gestation for women with a history of genital HSV but without recurrence during pregnancy is cost-effective 5
Pharmacokinetics in Pregnancy
- Maternal acyclovir pharmacokinetics in late gestation are similar to those of nonpregnant adults 6
- Peak and trough plasma concentrations of acyclovir in pregnant women may be slightly lower compared to non-pregnant adults but remain effective 4
- Acyclovir concentrates in amniotic fluid but does not accumulate in the fetus (mean maternal/infant plasma ratio at delivery is 1.3) 6
Family Planning Considerations
- HIV-infected persons should use latex condoms during every act of sexual intercourse to reduce the risk of exposure to HSV and other sexually transmitted pathogens 3
- Sexual contact should be avoided when herpetic lesions (genital or orolabial) are evident 3
- Susceptible women whose partners have oral or genital HSV infection should be counseled to avoid unprotected genital and oral sexual contact during late pregnancy 3
Special Considerations
- Acyclovir-resistant HSV strains are typically resistant to valacyclovir and famciclovir as well 3
- For acyclovir-resistant infections, intravenous foscarnet (40 mg/kg body weight every 8 hours until clinical resolution) is often effective 3
- Immunocompromised patients might require higher doses of antiviral drugs for effective treatment 1
- If lesions persist during acyclovir treatment, viral resistance should be suspected 1
Monitoring and Follow-up
- Women should inform healthcare providers who care for them during pregnancy about their HSV infection 1
- At the onset of labor, all women should be examined and questioned regarding symptoms of genital herpes 3
- Cesarean delivery is indicated for women with active genital lesions or prodromal symptoms at the time of delivery 1