Genital Herpes in Pregnancy: Management
Background
Neonatal herpes is rare but carries high morbidity/mortality. Most cases (75–85%) follow direct contact with infected genital secretions at birth; fewer follow postnatal exposure or, rarely, transplacental in-utero infection. Transmission risk depends on whether maternal infection is primary (first-ever HSV infection), non-primary first-episode (new acquisition of the second HSV type with pre-existing antibody to the other type), or recurrent (reactivation) — and on timing relative to delivery.
Management by Timing of Acquisition
First/second trimester acquisition (up to 27+6 weeks): if delivery is not anticipated within 6 weeks, manage expectantly with vaginal delivery anticipated. If delivery occurs within 6 weeks of acquisition, Caesarean section is recommended, as shedding may persist up to 6 weeks (occasionally longer) and neonatal transmission risk is high (~41%) in this scenario.
Third trimester acquisition (from 28 weeks) up to 4 weeks postpartum: Caesarean section is the recommended mode of delivery for all first (primary or non-primary) episodes in the third trimester, as seroconversion and protective antibody transfer are unlikely to complete before birth.
Primary/non-primary lesions at onset of labour: Caesarean is recommended. Neonatal herpes risk with vaginal birth is ~41% for primary and ~25% for non-primary first-episode infection. If Caesarean is declined, IV aciclovir 5 mg/kg every 8 hours should be given intrapartum to the mother, with IV aciclovir 20 mg/kg every 8 hours to the neonate.
Recurrent Genital Herpes
Recurrent lesions at delivery carry low neonatal transmission risk (0–3% with vaginal delivery), since pre-existing antibody is usually protective. Vaginal delivery should be offered where lesions are confidently recurrent (known HSV type, prior episodes, or supportive serology); Caesarean is not routinely required. Suppressive antivirals are recommended regardless of recurrences, reducing asymptomatic shedding and lesions at term (not proven to prevent neonatal HSV disease specifically).
Aciclovir/Valaciclovir Prophylaxis
Suppressive therapy from 32 weeks is now recommended for all with genital herpes (first-episode or recurrent): aciclovir 400 mg three times daily, or valaciclovir 500 mg twice daily, continued until delivery. For those at high risk of preterm delivery, start from 22 weeks (aciclovir 400 mg twice daily or valaciclovir 500 mg once daily), stepping up to standard 32-week dosing thereafter — a change from the older 36-week threshold. Aciclovir/valaciclovir are unlicensed in pregnancy but not linked to increased major birth defects; famciclovir should be avoided (insufficient safety data).
Preterm Prelabour Rupture of Membranes (PPROM, <37 weeks)
Primary/non-primary HSV with PPROM needs multidisciplinary discussion (obstetrics, GUM, neonatology); the neonate is managed as highest-risk. If managed conservatively, IV aciclovir 5 mg/kg every 8 hours is given until delivery, alongside prophylactic corticosteroids. Caesarean may still offer benefit if delivery occurs within 6 weeks of primary infection, despite prolonged membrane rupture.
High-Yield Exam Points
- Primary herpes in the third trimester, or within 6 weeks of delivery at any gestation → Caesarean recommended.
- Primary/non-primary infection before 28 weeks with delivery expected >6 weeks later → vaginal delivery appropriate.
- Recurrent lesions at labour → vaginal delivery generally appropriate (risk 0–3%); Caesarean not routine.
- Transmission risk: ~41% primary with lesions at vaginal delivery, ~25% non-primary first episode, 0–3% recurrent.
- Suppressive aciclovir/valaciclovir starts at 32 weeks (standard) or 22 weeks (high preterm-birth risk) — not 36 weeks as in older guidance.
- Intrapartum IV aciclovir (mother) + neonatal IV aciclovir if active first-episode lesions and Caesarean is declined.
Source: RCOG Green-top Guideline No. 30 (Archived — superseded by the Joint BASHH/RCOG National UK Guideline for the Management of Herpes Simplex Virus (HSV) in Pregnancy and the Neonate) (2024 update (published in *International Journal of STD & AIDS*, received 15 Aug 2024; this is the second edition, replacing the first joint BASHH/RCOG guideline of 2014, which itself replaced GTG No. 30))
Read the original on rcog.org.uk
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