HSV-2 and Pregnancy

Neonatal herpes: understanding the actual risk

Neonatal herpes (herpes infection in a newborn) is serious when it occurs. It can affect the skin, eyes, and mouth, and in severe cases can involve the central nervous system with significant complications. This is why HSV-2 in pregnancy gets careful clinical attention.

Here's important context on risk: neonatal herpes is rare. The CDC estimates it occurs in roughly 1 in 3,200 to 1 in 10,000 live births in the US. And the risk is very different depending on your specific situation.

The highest-risk scenario by far is acquiring a first HSV infection -- primary infection -- late in the third trimester of pregnancy. In that situation, the transmission risk to the baby during vaginal delivery is approximately 30-50%. That's the genuinely high-risk scenario that warrants the most concern.

For people who have had HSV-2 for a long time before pregnancy (recurrent infection), the risk is much lower. Approximately 1-3% without antiviral treatment. With suppressive therapy in the third trimester, risk drops further.

The reason for this difference: with longstanding infection, the mother has developed HSV-specific antibodies that cross the placenta and provide partial protection to the baby. With a primary infection late in pregnancy, those antibodies haven't had time to develop, and viral load during primary infection is typically much higher than during recurrence.

The takeaway: if you have had HSV-2 for years before becoming pregnant, your risk profile is completely different from someone who acquires a new infection during pregnancy. Both matter, but they're managed differently.

Primary vs. recurrent infection: the critical distinction

This distinction shapes almost every aspect of HSV-2 management during pregnancy, so it's worth understanding clearly.

Situation	Transmission risk at delivery	Management approach
Primary infection in third trimester	30-50% without intervention	Suppressive therapy, C-section strongly recommended regardless of active lesions
Recurrent HSV-2, lesions present at labor	Significantly elevated	C-section recommended
Recurrent HSV-2, no lesions at labor (no suppressive therapy)	~1-3%	Vaginal delivery generally appropriate
Recurrent HSV-2, on suppressive therapy from 36 weeks, no lesions at labor	Lower than 1-3%	Vaginal delivery generally appropriate

If you are HSV-negative and your partner has HSV-2, this is an important time to maintain consistent condom use throughout pregnancy. Acquiring primary HSV infection during pregnancy, especially in the third trimester, is the highest-risk scenario and the most important one to prevent.

Tell your OB. This is genuinely important.

If you're pregnant and have HSV-2, tell your OB. This isn't optional or a "nice to have." Obstetricians routinely manage HSV-2 in pregnant patients -- it's common enough that they handle it regularly and without judgment. But they need to know in order to manage your care appropriately.

Many people feel embarrassed or worry about how the conversation will go. That worry is understandable and almost always unfounded. Your OB's job is to keep you and your baby healthy. They're not there to judge how you got a very common virus.

Disclosing your HSV status allows your OB to develop a care plan that includes suppressive therapy timing, monitoring for active lesions as your due date approaches, and a delivery plan that accounts for your situation. None of this is frightening -- it's standard care for a manageable situation.

Suppressive therapy during pregnancy

Current obstetric guidelines recommend antiviral suppressive therapy starting at 36 weeks of pregnancy for people with known HSV-2. The goals are:

• Reduce the likelihood of active lesions at delivery (which would require C-section)
• Reduce asymptomatic viral shedding at the time of labor
• Reduce the overall viral load in the birth canal during delivery

The two most commonly used options are:

• Acyclovir 400mg three times daily starting at 36 weeks
• Valacyclovir 500mg twice daily starting at 36 weeks

Both have been studied in pregnancy. Acyclovir has the larger body of safety data in pregnancy and is often the first choice. Valacyclovir is converted to acyclovir in the body and is also considered safe. Both are Category B medications for pregnancy (animal studies show no harm and there are no well-controlled human studies showing risk).

Studies have shown that suppressive therapy in the final weeks of pregnancy significantly reduces the rate of HSV recurrence at delivery. This matters practically because fewer active outbreaks at labor means fewer C-sections and lower transmission risk.

If you're already on daily suppressive therapy for your own outbreak management, talk to your OB about continuing or adjusting your regimen during pregnancy. Don't stop antiviral medication without discussing it with your provider first.

C-section decisions

The decision about C-section in the context of HSV-2 comes down primarily to what's happening at the time labor begins.

C-section is recommended when:

• Active genital herpes lesions are present at the onset of labor
• Prodrome symptoms are present (tingling, burning, itching that precede an outbreak) at the onset of labor
• Primary HSV infection occurred late in the third trimester (even without active lesions at delivery, the risk profile is different)

C-section is generally not required when:

• No active lesions or prodrome symptoms at labor onset
• Recurrent HSV-2 with longstanding infection
• Suppressive therapy has been maintained in the third trimester

The evidence is clear that C-section significantly reduces neonatal herpes transmission when active lesions are present. The evidence also supports that not every person with HSV-2 needs C-section -- that would be an overuse of a surgery with its own risks and recovery.

Your OB will assess this when labor begins. The key preparation on your end: know your own prodrome signs (the warning symptoms before an outbreak), so you can communicate clearly about whether any symptoms are present. See our symptoms page for what prodrome typically feels like.

What if your partner has HSV-2 and you don't

This is actually one of the more important scenarios during pregnancy. If your partner has HSV-2 and you don't have confirmed HSV-2 status yourself, there are a few key points:

• Use condoms consistently throughout pregnancy, including in the third trimester. Primary HSV infection in late pregnancy is the highest-risk scenario.
• Your partner should consider staying on suppressive therapy during your pregnancy to reduce their shedding and transmission risk.
• Avoid oral sex if your partner has oral HSV (cold sores) -- genital HSV-1 infection during pregnancy carries similar risks to HSV-2.
• Get tested for HSV at the start of pregnancy if you haven't been tested. Knowing your status matters. See our testing guide for how to get an accurate result.

Tell your OB about your partner's HSV-2 status. They may recommend testing for you and can advise on appropriate precautions.

What to tell your OB at your first appointment

Come prepared with this information:

• That you have HSV-2 (or HSV-1, be specific about type if you know it)
• Approximately how long you've had the virus (to establish this is a recurrent, not primary, infection)
• How frequently you have outbreaks normally
• Whether you're currently on antiviral medication and what dose
• Your partner's HSV status if relevant
• Any previous pregnancy experiences with HSV if applicable

With this information, your OB can develop an appropriate care plan. For most people with recurrent HSV-2, this means monitoring, suppressive therapy starting at 36 weeks, and a plan for delivery. It doesn't need to be more complicated than that, and it's completely manageable.

Related: Treatment options | Acyclovir guide | Valacyclovir guide | How to get tested