Yes — for a pregnant person already known to carry HSV-2, taking a daily antiviral like valacyclovir in the final weeks of pregnancy is standard care because it suppresses outbreaks and viral shedding near the due date, which lowers the chance the baby contacts the virus during a vaginal birth. It doesn't cure herpes, and it works alongside careful delivery planning.
about 12%
but well controlled
| Item | Value |
|---|---|
| Adults 14–49 with HSV-2 | ~1 in 8 — about 12% |
| Unaware they have it | ~87% |
| Daily antivirals cut spread | ~50% |
| Cure | none — but well controlled |
Why herpes matters specifically in pregnancy
Genital herpes is caused by two related viruses, herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2), and once you have either, it's lifelong — antivirals control it but never clear the latent virus CDC. For most adults that's a manageable nuisance; in pregnancy the stakes change because the virus can reach a newborn during delivery. Timing drives the risk most. A person who first catches HSV-2 late in pregnancy hasn't yet made protective antibodies to hand off to the baby, so a brand-new infection near term is far more dangerous than a long-standing one.
This matters because herpes spreads quietly. Most people with HSV-2 have no symptoms or very mild ones, and the majority never get diagnosed, so a pregnant person can carry it, or catch it from a partner mid-pregnancy, without knowing. If you're trying to sort out what an outbreak even looks like, our guide to genital herpes symptoms walks through the blisters, sores, and flu-like first episode in plain terms.
What the risk to the baby actually is
The serious outcome is neonatal herpes, a potentially deadly infection in a newborn whose immature immune system can't contain the virus. It can attack the skin, eyes, and mouth, or spread to the brain and internal organs, which is why it's treated as an emergency. Herpes acquired during pregnancy can also cause miscarriage or preterm delivery. These outcomes are uncommon, but they're why clinicians take a known herpes diagnosis in pregnancy seriously.
Transmission usually happens at delivery, when the baby passes through a birth canal where the virus is actively shedding. A visible sore isn't the only danger. People with HSV-2 shed virus on about 10% of days even with no outbreak, and most of that shedding leaves no sore at all JAMA. A clear-looking exam doesn't guarantee zero virus, which is why suppressive antivirals and delivery planning exist.
Should you be screened for herpes during pregnancy?
If you have no symptoms and no known history, current guidance says no. The U.S. Preventive Services Task Force recommends against routine blood-test (serologic) screening for genital herpes in asymptomatic adolescents and adults, including pregnant people — a Grade D recommendation USPSTF, 2023. The blood tests have high false-positive rates, and a wrong-positive result during pregnancy causes anxiety, relationship strain, and unnecessary interventions without a matching benefit.
That's different from testing when you actually have a sore. If lesions appear, an in-person clinic visit during the outbreak gives the most reliable diagnosis, because the lab can swab the sore directly. If you've had a recent exposure and aren't sure when results become meaningful, see when to test after exposure, and you can arrange a visit through get tested.
Is Valtrex (valacyclovir) safe to take while pregnant?
There are three FDA-approved antivirals for herpes — acyclovir, valacyclovir (Valtrex), and famciclovir — and acyclovir and valacyclovir are the ones used in pregnancy, with a long track record. They're cheap generics, which keeps daily suppressive therapy realistic for most families CDC. These drugs control symptoms and reduce shedding; they don't cure the infection or change how it behaves once you stop. If the cure question keeps nagging, our explainer on is genital herpes curable? what treatment does lays out what antivirals can and can't do.
For someone with a known herpes history, the usual approach is daily suppressive antiviral therapy started in the last stretch of pregnancy and continued until delivery. The goal is to suppress outbreaks and asymptomatic shedding right when it counts, so the baby is less likely to meet the virus on the way out. Suppressive therapy cuts recurrences by 70%–80% in people who get frequent outbreaks, the same mechanism that makes it useful near term.
| Approach | How it's taken | Best for |
|---|---|---|
| Episodic therapy | Pills started at the first sign of an outbreak to shorten and ease the sores | Occasional, predictable outbreaks earlier in pregnancy |
| Suppressive therapy | A daily antiviral, typically begun in the final weeks and continued to delivery | Anyone with a known herpes history, to cut shedding before birth |
How transmission is reduced at delivery
Two tools work together. Late-pregnancy suppressive antiviral therapy lowers the odds of an active outbreak or detectable shedding when labor starts. The second is a careful exam in labor: if there's an active genital lesion or prodromal symptoms (the tingling, itching, or pain that warns an outbreak is coming) at the time of delivery, a cesarean is generally recommended to keep the baby out of the infected birth canal. With no lesions and no prodrome, a vaginal birth is usually appropriate.
It's worth knowing why daily antivirals are trusted to reduce passing the virus to another person. In a randomized trial of couples where one partner had HSV-2 and the other didn't, suppressive valacyclovir lowered the risk of transmitting HSV-2 to the partner by about 48% Corey et al.. That's the same suppression-of-shedding effect being put to work before a birth — fewer days of virus present means fewer chances to pass it on.
The most common mistake parents make is assuming no sore means no risk. Herpes spreads from people who have no symptoms at the moment of contact, so both honest disclosure between partners and — when chosen — daily suppressive therapy matter. If your partner has herpes and you're pregnant or planning to be, avoiding a new infection late in pregnancy is its own priority; reviewing herpes outbreak triggers & how to prevent them can help you both reduce flares and exposures.
When to see a clinician
Tell your prenatal provider if you or your partner has ever had genital herpes, even years ago, because that history shapes your delivery plan. Reach out promptly if you get a first-ever genital outbreak during pregnancy, since a brand-new infection late in pregnancy carries the highest risk to the baby. And during labor, report any tingling, itching, pain, or visible sores so your team can decide on the safest delivery route. This isn't a reason to panic; it's a reason to tell the right person at the right time.