Genital herpes during pregnancy: what matters for birth and the baby
A genital herpes diagnosis during pregnancy often triggers fear about the baby and the birth. Yet for most people who had herpes before pregnancy, the risk of passing the virus to a newborn is very low. What matters most is not simply whether HSV is present, but when the first infection occurred, whether symptoms are present near delivery, and whether the maternity team knows about them.
Why the timing of the first infection matters
Neonatal herpes occurs when a baby acquires HSV-1 or HSV-2, most often during birth. It is rare but can be serious. According to the CDC, transmission risk is about 30–50% when genital herpes is acquired near delivery, compared with less than 1% in people with recurrent herpes or a first episode during the first half of pregnancy.
Antibodies help explain the difference. After an older infection, maternal antibodies cross the placenta and help protect the baby. When infection is acquired shortly before delivery, there may not be enough time for this protection to develop.
What to do if symptoms appear
Painful genital or anal blisters or ulcers, burning, tingling, or pain before a rash appears should prompt a call to an obstetric clinician, primary care clinician, or sexual health clinic as soon as possible. A possible first episode in the second half of pregnancy is especially important to report. If labor has begun or the waters have broken, contact the maternity unit immediately and mention the symptoms.
When a lesion is present, the most useful test is usually a swab from the lesion using a nucleic acid amplification test, commonly PCR. A negative result from an old or healing sore does not always rule out HSV because viral shedding is intermittent. A blood test cannot identify the site of an HSV-1 infection, and false-positive results occur. The USPSTF and CDC therefore advise against routine serologic screening in people without symptoms, including pregnant people. Type-specific testing can still help in selected situations, such as when a partner has HSV; that decision should be made with a clinician.
Treatment during pregnancy
Genital herpes can be treated during pregnancy. Antiviral medicines shorten and lessen symptoms but do not remove latent virus from the body. The CDC considers acyclovir acceptable in all trimesters and while breastfeeding; a clinician should choose the medicine and regimen after considering gestational age, episode severity, and kidney function.
People with recurrent genital herpes are often offered suppressive treatment late in pregnancy to reduce the chance of an outbreak during labor. The start date differs across national guidance: the CDC uses 36 weeks, while the updated UK patient guidance from RCOG uses 32 weeks, or earlier when preterm birth is more likely. Do not start or change treatment without professional advice.
Is a cesarean birth always required?
No. A history of genital herpes alone does not rule out vaginal birth. If there are no lesions or prodromal symptoms during labor, the CDC supports vaginal delivery. When genital lesions or prodromal symptoms are present, the CDC recommends cesarean delivery to reduce transmission risk, although it cannot remove the risk completely.
Guidelines differ. The 2024 UK guideline recommends offering vaginal birth in recurrent infection even if a recurrence is present, because the absolute risk to the baby is very low; planned cesarean birth is more often recommended for a first episode after 28 weeks, especially within six weeks of the due date. ACOG, whose bulletin was reaffirmed in 2026, also allows cesarean delivery to be offered after a first episode in the third trimester because viral shedding may be prolonged. The birth plan should follow local guidance and account for the type and timing of the episode and individual circumstances.
Reducing the risk of a new infection late in pregnancy
- Avoid vaginal, anal, or oral sex when a partner has blisters, sores, tingling, or burning.
- If a partner has genital herpes, discuss condoms and additional precautions with a clinician, particularly for the third trimester.
- If a partner has oral herpes, avoid receiving oral sex during the third trimester; oral HSV-1 can cause genital infection.
- Tell the maternity team about a previous diagnosis even if there has not been an outbreak for years.
Condoms reduce but do not eliminate risk because HSV can shed from skin they do not cover.
After birth: when the baby needs urgent care
HSV is not transmitted through breast milk, and breastfeeding is usually possible. A baby can, however, acquire HSV by touching an active skin sore. Everyone handling a newborn should wash their hands; a person with a cold sore should not kiss the baby or touch the sore and then the infant. A lesion on the breast requires prompt advice from a healthcare professional about safe feeding.
Seek urgent medical care if, during the first six weeks, the baby becomes unusually sleepy or irritable, feeds poorly, develops a fever, blisters or another rash, has difficulty breathing, or has a seizure. Tell clinicians about maternal or household herpes. Neonatal herpes can begin without typical blisters, so the baby’s overall condition matters.
A short plan for a pregnant person with HSV
- Tell the obstetric clinician or midwife about genital herpes early in prenatal care.
- Seek same-day advice for new ulcers or a possible first episode instead of waiting for a routine visit.
- Discuss late-pregnancy suppressive treatment and a birth plan in advance.
- At the start of labor, report any rash, pain, burning, or tingling.
- After birth, use careful hand hygiene and know the signs that require immediate assessment.
Herpes is not a sign of poor hygiene or anyone’s fault. A clear plan with the healthcare team is more useful than fear, self-testing, or self-treatment.
Sources
- RCOG: Genital herpes and pregnancy, 2025
- CDC: Herpes — STI Treatment Guidelines
- WHO: Herpes simplex virus
- USPSTF: Serologic screening for genital herpes
- ACOG: Management of Genital Herpes in Pregnancy
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