Genital Herpes in Pregnancy: What Changes
Why timing decides everything, what suppressive treatment from 36 weeks is for, when a caesarean is recommended, and the newborn signs worth knowing.
Part of the Complete Genital Herpes Guide.
Key fact: The risk to the baby depends on when you caught herpes, not whether you have it. Longstanding herpes passes protective antibodies to the baby and vaginal birth is usually appropriate; a first infection in the third trimester is the situation where planned caesarean is recommended.
Why herpes in pregnancy is handled differently
For the overwhelming majority of pregnancies affected by herpes, the outcome is a normal delivery and a healthy baby. The care differs from usual because of one specific risk: neonatal herpes, a rare but serious infection that can occur if a baby is exposed to the virus around the time of birth.
The risk depends almost entirely on when the infection was acquired. Someone who has had herpes for years has antibodies that cross the placenta and protect the baby, making transmission unlikely. Someone who catches it for the first time late in pregnancy has not yet developed those antibodies, and that is the situation guidance is built around.
The single most useful thing you can do is tell your midwife or obstetrician that you have genital herpes, or have had it in the past, even if you have had no symptoms for years. It changes nothing about how you are treated day to day, and it means the right plan is in place for delivery.
If you already had herpes before pregnancy
This is the common and reassuring scenario. Your antibodies protect the baby, and the risk of neonatal herpes is low even if you have a recurrence around the time of birth.
- Recurrences can be treated in pregnancy, and aciclovir is the antiviral with the longest safety record
- Suppressive aciclovir from 36 weeks is commonly offered to reduce the chance of an outbreak being present at delivery; NHS information refers to treatment from around 32 weeks and the RCOG guideline to 36 weeks, so follow your team’s plan
- Vaginal birth is usually appropriate, even with a recurrence at the time of labour. UK guidance notes the evidence that caesarean reduces transmission in recurrent herpes is uncertain, so it is not routinely recommended
- Lesions at delivery should be mentioned to the team, who will weigh the options with you
If you catch it for the first time during pregnancy
This needs prompt assessment, and the timing matters a great deal.
| When | What usually happens |
|---|---|
| First or second trimester | Treated with aciclovir; suppressive treatment usually offered from 36 weeks; vaginal birth normally planned, since antibodies will have developed by delivery |
| Third trimester | Referral to an obstetrician, treatment with aciclovir, and planned caesarean recommended — particularly within six weeks of the due date, when antibodies may not have developed in time |
| Around the time of labour | Urgent obstetric involvement; caesarean is usually advised, and the baby is monitored closely after birth |
If you develop genital blisters or ulcers for the first time while pregnant, contact your midwife or maternity unit rather than waiting — a swab while lesions are present is what establishes the diagnosis, and the timing of treatment affects the delivery plan.
Preventing a first infection late in pregnancy
Because a new infection in the third trimester carries the highest risk, avoiding one matters. If your partner has herpes or cold sores and you do not, it is worth discussing condoms for the remainder of the pregnancy, avoiding sex during any outbreak, and avoiding receiving oral sex if your partner has, or is developing, a cold sore — HSV-1 from a cold sore can cause genital infection, which is covered in HSV-1 vs HSV-2.
After the birth
Neonatal herpes is rare, but it is worth knowing what prompts urgent review in the newborn period: a baby who is feeding poorly, floppy or irritable, has a fever or low temperature, develops blisters on the skin, eyes or mouth, or simply seems unwell. Any of these needs immediate medical assessment.
Seek urgent medical help for a newborn who has blisters or sores, a fever, is unusually sleepy or floppy, is feeding poorly, or seems generally unwell. Neonatal herpes is uncommon but time-critical, and early treatment matters. Trust your instinct and be seen.
Breastfeeding is safe unless there is a herpes lesion on the breast itself. Ordinary precautions apply at home: wash your hands, avoid touching lesions and then the baby, and cover any cold sore rather than kissing the baby while one is present.
For the medicines themselves, see aciclovir vs valaciclovir; for a first episode outside pregnancy, see your first outbreak.
Frequently Asked Questions
Is genital herpes dangerous in pregnancy?
For most pregnancies, no — if you had herpes before conceiving, your antibodies cross the placenta and protect the baby, and a normal delivery is usually appropriate even with a recurrence. The situation that needs careful management is catching herpes for the first time late in pregnancy, when those protective antibodies have not yet developed.
Can I take aciclovir while pregnant?
Yes, when prescribed. Aciclovir has the longest safety record of the antivirals and is what UK guidance uses in pregnancy, both for treating an episode and as suppressive treatment in the last weeks to reduce the chance of lesions at delivery. Always tell the prescriber you are pregnant.
Will I need a caesarean?
Usually not if you had herpes before pregnancy — UK guidance notes the evidence that caesarean reduces transmission in recurrent herpes is uncertain, so vaginal birth is normally planned. A planned caesarean is recommended when a first episode occurs in the third trimester, particularly within six weeks of the due date.
When does suppressive treatment start?
Commonly in the last weeks of pregnancy: NHS information refers to antiviral treatment from around 32 weeks and the RCOG guideline to aciclovir from 36 weeks until delivery. The aim is to reduce the chance of an outbreak being present when you give birth. Follow the plan your maternity team sets out.
Should I tell my midwife?
Yes, even if you have had no symptoms for years. It does not change your day-to-day care, and it means the delivery plan accounts for it. It is also worth mentioning if your partner has herpes or cold sores and you do not, because avoiding a new infection late in pregnancy is the priority.
Can I breastfeed?
Yes, unless there is a herpes lesion on the breast itself. Ordinary precautions matter: wash your hands, do not touch a lesion and then the baby, and if you have a cold sore, cover it and avoid kissing the baby until it has healed.
References
- NHS. Genital herpes. nhs.uk
- British Association for Sexual Health and HIV. UK national guideline for the management of anogenital herpes. bashh.org
- BASHH and Royal College of Obstetricians and Gynaecologists. National UK guideline for the management of herpes simplex virus (HSV) in pregnancy and the neonate (2024 update). journals.sagepub.com
- Royal College of Obstetricians and Gynaecologists. Management of genital herpes in pregnancy. rcog.org.uk
- National Institute for Health and Care Excellence. Clinical Knowledge Summary: Herpes simplex — genital. cks.nice.org.uk
Medical disclaimer: This article is for informational purposes only and does not constitute medical advice. Genital symptoms have several possible causes and herpes is only one of them; diagnosis needs a clinician and usually a swab. Always consult a qualified healthcare professional for diagnosis and treatment. In a medical emergency, call 999.