What valacyclovir (Valtrex) dosing regimen is recommended for suppressive therapy in a pregnant HSV‑2 seropositive woman with recurrent genital herpes to prevent recurrences and reduce the need for cesarean delivery?

Valacyclovir Dosing for HSV-2 Prevention in Pregnancy

For pregnant women with recurrent HSV-2 infection, start valacyclovir 500 mg orally twice daily at 36 weeks gestation and continue until delivery to reduce clinical recurrences and cesarean delivery rates. 1, 2

Recommended Suppressive Regimen

• Valacyclovir 500 mg orally twice daily starting at 36 weeks gestation until delivery is the standard regimen 1, 2
• Alternative option: Acyclovir 400 mg orally three times daily from 36 weeks until delivery, which has the most extensive pregnancy safety data 1, 2

Clinical Efficacy

• This regimen reduces clinical HSV recurrences at delivery from 27-36% to 5-11% 2
• Cesarean delivery rates decrease by approximately 60-70% when suppressive therapy is used 2
• In randomized trials, only 4% of women on valacyclovir had recurrences at delivery versus 13% on placebo (P=0.009) 3
• HSV shedding detected by culture was 2% in the valacyclovir group versus 9% in placebo (P=0.02) 3

Who Should Receive Suppressive Therapy

• Women with documented recurrent genital herpes during the current pregnancy should receive suppressive therapy starting at 36 weeks 1, 2
• Women with a history of frequent recurrences (≥6 per year) should receive suppressive therapy 2
• Routine suppressive therapy is NOT recommended for women with a history of genital herpes but no recurrences during the current pregnancy 2, 4, 5

Safety Profile

• Acyclovir is pregnancy category B with decades of safety data showing no pattern of adverse pregnancy outcomes or major congenital anomalies 1, 2
• One case-control study found increased odds of gastroschisis (OR 4.7) when antiherpes medications were used from one month before conception through the third month of pregnancy, but this study had significant confounders and recall bias 1
• The risk-benefit analysis strongly favors initiating suppressive therapy at 36 weeks, avoiding first-trimester exposure while maximizing prevention of neonatal transmission 2

Critical Management at Labor Onset

• If visible genital lesions or prodromal symptoms are present at labor onset, proceed with cesarean delivery regardless of suppressive therapy 1, 2, 5
• Perform careful examination of the vaginal canal, cervix, and external genitalia at labor onset to identify any active lesions 2
• Recurrent HSV at delivery carries a 1-3% neonatal transmission risk, compared to 30-50% for primary infection 2, 5

Neonatal Surveillance

• All newborns with maternal HSV exposure should have surveillance cultures of conjunctiva, oral cavity, nasopharynx, and rectum collected at 24-48 hours after birth 2
• Routine empiric acyclovir is NOT recommended for asymptomatic infants born to mothers with recurrent HSV on suppressive therapy who delivered by cesarean without lesions 2
• Any infant with positive surveillance cultures or clinical signs should receive IV acyclovir 20 mg/kg three times daily immediately 2

Common Pitfalls to Avoid

• Do not start suppressive therapy before 36 weeks in women with typical recurrent HSV, as this provides no additional benefit and increases medication exposure 1, 2
• Do not rely on prenatal viral cultures to guide delivery management—they do not predict viral shedding at delivery 2
• Do not assume suppressive therapy eliminates the need for cesarean delivery if active lesions are present at labor 1, 2
• Do not forget to counsel patients that transmission can still occur despite suppressive therapy, and abstinence from sexual activity during prodrome or active lesions is essential 6