Yes: for a pregnant person with recurrent genital herpes, daily valacyclovir (or acyclovir) started in late pregnancy lowers the chance the baby is exposed during birth. It works by suppressing outbreaks and viral shedding at term, which reduces both active lesions at delivery and the need for a cesarean. It cuts the risk without eliminating it.
Key figures
- Most people
- mild / none
- Test
- swab a sore
- NAAT or culture
- Antivirals
- control
- not a cure
- Screening
- not advised
- USPSTF Grade D
| Item | Value |
|---|---|
| Most people | mild / none |
| Test | swab a sore: NAAT or culture |
| Antivirals | control: not a cure |
| Screening | not advised: USPSTF Grade D |
Why herpes matters in pregnancy
Genital herpes is caused by herpes simplex virus type 1 (HSV-1) or type 2 (HSV-2), and HSV-2 is the type more likely to recur and to shed virus from the genital skin CDC. The infection is lifelong; antivirals control it but don't cure it. In most people it causes no symptoms, or symptoms so mild they go unnoticed. A parent who doesn't know they carry the virus can still pass it to a newborn, which is what raises the stakes in pregnancy.
The danger isn't the virus circulating quietly in an adult. The risk is concentrated at delivery. As the baby passes through the birth canal, contact with infectious fluid or a lesion can transfer the virus to a newborn whose immune system isn't yet ready to fight it. So the conversation about herpes in pregnancy comes down to timing, shedding, and the route of delivery.
What herpes can do to the baby
Neonatal herpes is a potentially deadly infection in the newborn. Depending on when and how the baby is exposed, the infection can stay limited to the skin, eyes, and mouth, or it can spread to the brain and other organs. Those latter forms cause lasting harm or death. Infection during the pregnancy itself, rather than at birth, may also lead to miscarriage or preterm delivery.
The single biggest risk factor is a brand-new (primary) herpes infection acquired late in pregnancy. If you catch herpes for the first time near your due date, your body hasn't yet made the protective antibodies that normally pass to the baby, and you may be shedding large amounts of virus at delivery. A long-standing, recurrent infection carries a far lower risk to the baby, because those protective antibodies are already on board. Which situation you're in shapes the whole plan.
Is routine herpes screening recommended in pregnancy?
No. The U.S. Preventive Services Task Force recommends against routine blood (serologic) screening for genital herpes in people without symptoms, including pregnant people: a Grade D recommendation USPSTF, 2023. The blood test produces a high rate of false positives, and the anxiety, relationship strain, and unnecessary follow-up from a wrong result outweigh the small benefit. A positive antibody test also can't tell you whether you'll have a lesion the day you deliver.
That doesn't mean herpes is ignored in prenatal care. Your clinician should ask about your history and your partner's, and examine you near term if you've ever had genital sores. New symptoms in pregnancy are different, testing then confirms an active infection rather than screening a healthy person. If you're unsure what your sores are, our guide on herpes vs. contact dermatitis can help you decide whether to come in, and you can learn what to expect from herpes testing before your visit.
Safe herpes treatment during pregnancy
Three FDA-approved antivirals treat genital herpes: acyclovir, valacyclovir, and famciclovir. In pregnancy, the two used are acyclovir and valacyclovir, both have long safety records and are favored over famciclovir. They come in two strategies: episodic therapy (a short course taken when an outbreak starts) and suppressive therapy (a daily pill that keeps the virus quiet).
For pregnancy, suppressive therapy is the workhorse, started at 36 weeks to cut viral shedding and lesions at delivery. The recommended regimens are acyclovir 400 mg three times daily or valacyclovir 500 mg twice daily CDC. These are inexpensive generics, so cost is rarely the barrier. Feeling fine doesn't mean you're not contagious: people with HSV-2 shed virus on a meaningful share of days with no sore at all, and the infection spreads that way. A daily pill matters even when you look clear.
How valacyclovir reduces transmission at delivery
For women with recurrent genital herpes, the CDC notes that antiviral treatment started at 36 weeks' gestation reduces the frequency of cesarean delivery by diminishing recurrences at term. The daily pill makes an active outbreak, and the viral shedding that comes with it, far less likely on the day you deliver. ACOG makes the same recommendation: offer suppressive acyclovir or valacyclovir at or beyond 36 weeks to decrease lesions and shedding at delivery ACOG.
Suppressive antivirals are proven shedding-reducers. In a randomized trial of couples where one partner had HSV-2, daily valacyclovir lowered transmission to the other partner by about 48% NEJM via PMC. The same anti-shedding effect protects a newborn: less virus present at the birth canal means less to expose the baby to. CDC also notes that people who carry HSV-2 but never had symptoms shed about half as much as those with symptomatic disease JAMA, part of why a primary late-pregnancy infection is so much riskier than a quiet, long-standing one.
What suppressive therapy does and doesn't do is worth being clear about:
- It lowers the chance of an active lesion and high viral shedding at term, so it reduces, but does not erase, the risk of passing herpes to the baby.
- It increases the chance you can deliver vaginally, because fewer women have visible lesions that would otherwise call for a cesarean.
- It does not cure the infection, change how often you'll get outbreaks after delivery, or clear the latent virus that lives in your nerves for life.
- It is not a substitute for the delivery-day exam. If there's an active genital sore or prodrome (the tingling, burning warning before an outbreak) when labor starts, a cesarean is usually recommended regardless of pills taken earlier.
| Approach | When it's used | What it's for at delivery |
|---|---|---|
| Suppressive antiviral from ~36 weeks (valacyclovir or acyclovir) | Recurrent genital herpes, started in late pregnancy | Fewer outbreaks and less shedding at term; lowers the odds of needing a cesarean |
| Cesarean delivery | Active genital lesion or prodrome at the onset of labor | Avoids direct contact between the baby and infectious lesions in the birth canal |
| No herpes history, no symptoms | Routine prenatal care | No suppressive pills and no antibody screening recommended (Grade D) |
When to see a clinician
Get in promptly if you're pregnant and notice new genital blisters, painful sores, or flu-like symptoms with body aches and swollen glands. A first outbreak late in pregnancy is the scenario that most changes the plan. A clinic visit while a sore is present gives the most reliable diagnosis, since the virus can be sampled directly from the lesion. Don't wait for it to heal; the sores can take a week or more to clear and the window to confirm closes as they do.
Also reach out if your partner has herpes and you're not sure of your own status, or if you've had genital sores before and want to plan late-pregnancy suppression. If a possible exposure is recent, our guide on when to test after exposure explains the timing, and you can get tested for the broader panel that matters in pregnancy. Knowing your symptoms, see genital herpes symptoms, helps you describe what's happening accurately.
Keep exploring on EasySTD: your risk of an STD, what STD testing costs and Genital Herpes testing.