Quick Answer: If you have a herpes outbreak while pregnant, the risk to your baby is highest if it’s a first-time infection in late pregnancy. Recurrent HSV carries lower risk, especially without active genital lesions during labor. Obstetricians will typically offer suppressive antiviral therapy starting around 36 weeks and may recommend a cesarean delivery if lesions or prodromal symptoms are present at labor onset. But many pregnancies with herpes proceed without transmission , the key is close monitoring, timely testing, and individualized delivery planning.
Understanding Herpes in Pregnancy: Types and Timing
Herpes Simplex Virus (HSV) comes in two main types: HSV-1 (often associated with oral herpes) and HSV-2 (classically genital). Either type can cause genital infections. But in pregnancy, the timing of infection and whether it’s your first episode (primary) or a recurrence (reactivation) make all the difference.
These distinctions matter because your body’s immune response and the timing of viral shedding differ, which in turn influences how likely the virus is present in genital secretions at labor.
Primary infection means you’ve never had HSV before, no antibodies, no defense. Recurrent infection means you’ve had it before, your immune system recognizes it, and the viral shedding is lower and shorter in duration. If you contract herpes for the first time in the third trimester, that’s the highest-risk window because your body doesn’t have time to build protection for the baby.
How Common Is Neonatal Herpes?
One of the scariest potential outcomes is neonatal herpes, when HSV infects the baby around the time of birth. But it remains rare. In the U.S., the estimated rate is about 15.7 cases per 100,000 births. That means more than 6,300 babies are born for every one who develops this infection.
Most babies who get sick do so during delivery, not while they are still in the womb. That's why managing your work is so important. This is how transmission breaks down:
| Mode of Transmission | Estimated Share | Key Details |
|---|---|---|
| During labor (intrapartum) | ~85% | Most common form, exposure through genital tract during delivery. |
| After birth (postnatal) | 10–15% | From caregivers with oral herpes or contact with lesions. |
| Before birth (in utero) | <5% | Rare, but possible. May cause miscarriage or birth defects. |
Table 1. Transmission routes for neonatal herpes and how they influence prevention strategies.
When to Be Worried: What Raises the Risk
Not all herpes outbreaks in pregnancy mean danger. But certain factors increase the chance of the virus being passed to your baby. Here’s when to pay close attention:
If you’ve never had herpes before and contract it late in pregnancy , especially the last six weeks , your body hasn’t built antibodies yet. That means more virus can be shed during labor, and the baby has no protection. This is when doctors get most concerned.
Visible sores or even just a tingling or burning sensation (known as prodrome) at the start of labor may signal viral activity. In those cases, many OBs recommend a cesarean delivery to reduce the baby’s exposure.
Other risks include your water breaking too early (prolonged rupture of membranes) and the use of fetal monitoring tools that can introduce virus directly into the baby’s skin. Even without symptoms, viral shedding can happen , that’s why timing, history, and testing all matter.
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Testing in Late Pregnancy: What to Expect
At around 36 weeks, many OBs will swab the vaginal and cervical area to check for active herpes virus. This isn’t the same as a blood test. It checks for shedding, meaning whether the virus is currently active, even if you have no symptoms.
If this swab is positive, your provider may recommend a cesarean. If it’s negative and you have no signs of an outbreak during labor, a vaginal delivery may still be considered safe.
Serology (blood tests) may be done if you suddenly have symptoms and don’t know your status. However, these aren’t routinely used in pregnancy unless necessary, because they only indicate exposure, not whether the virus is active.
What You Can Do: Suppressive Therapy and Safety
If you’ve had herpes before pregnancy, or even if this is your first outbreak late in pregnancy, your provider may recommend suppressive antiviral therapy starting at 36 weeks. This helps reduce viral shedding and the chance of an outbreak during labor.
The two most commonly prescribed medications are acyclovir and valacyclovir. These drugs are considered safe in pregnancy. Research from the Antiretroviral Pregnancy Registry and other large cohort studies shows no increased risk of birth defects with either one.
Typical dosing is:
| Medication | Common Dose | Purpose |
|---|---|---|
| Acyclovir | 400 mg, 3x per day | Suppress outbreak, reduce shedding |
| Valacyclovir | 500 mg, 2x per day | More convenient option with similar effect |
Table 2. Suppressive therapy options commonly used during pregnancy.
If an outbreak is severe or it’s your first time being infected during pregnancy, your provider may start antivirals earlier than 36 weeks. This decision depends on your individual history and symptoms.
Cesarean or Vaginal Birth: What Determines the Plan
The biggest question many parents ask is: if I have herpes, do I have to have a C-section?
The answer depends on three key things at the time labor begins:
First, are you showing symptoms? If you have visible lesions or prodromal symptoms (burning, tingling), your OB will likely recommend cesarean delivery. This minimizes the baby's exposure to the virus in the birth canal.
Second, do you have a known history of HSV and have you been taking suppressive therapy? If so, and you’re not shedding virus and have no signs at delivery, vaginal birth is usually considered safe.
Third, did your water break early? When membranes are ruptured for more than four to six hours, especially if you're shedding virus, risk of transmission goes up. Your provider may adjust the delivery plan based on timing and symptoms.
While cesarean reduces risk, it doesn’t eliminate it entirely. But when used in the right context, it can be life-saving for the newborn.
Real-Life Choices: Carmen and Daniela
Carmen was 35 weeks pregnant when she experienced her first-ever herpes outbreak. She had painful sores and flu-like symptoms, and bloodwork confirmed it was a primary infection. Her OB started her on valacyclovir immediately. At 38 weeks, Carmen still had tingling and a healing sore. She had a planned C-section. Her baby was monitored closely and tested after birth , all clear.
Daniela knew she had HSV-2 before she got pregnant. Her outbreaks were rare. She began suppressive therapy at 36 weeks as advised. When labor started at 39 weeks, she had no symptoms and her swabs had been negative. She delivered vaginally, with no complications. Her baby had no signs of infection and went home within 48 hours.
These two stories show how personalized the care plan can be. Your doctor will consider your history, symptoms, and test results , not just the presence of a diagnosis.
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After Delivery: What Happens to the Baby
If there's any concern about herpes exposure during birth, your baby's care team will act quickly. In many hospitals, newborns are swabbed in the first 24 hours after birth , from the mouth, eyes, skin, and sometimes rectum. If the delivery was low-risk and there were no signs of shedding or lesions, the baby may not need testing.
But if you had active lesions or a suspected first outbreak near labor, your baby may undergo blood tests, a spinal tap, and even a full course of antiviral therapy just to be safe. The medication used is IV acyclovir, and it’s effective when given early. Treatment usually lasts 14 to 21 days depending on whether symptoms are present and what areas of the body are involved.
Most babies do very well, especially when exposure is identified and treatment begins right away. But untreated neonatal herpes can be devastating , even fatal , which is why this cautious approach is used.
What If the Outbreak Happens Earlier?
Outbreaks in the first or second trimester may feel less urgent, but they still matter. If this is your first-ever herpes infection and it happens in the first half of pregnancy, the virus might impact your immune system and increase the risk of miscarriage or preterm labor. These outcomes are rare, but they’ve been documented in case studies and medical literature.
If you already had HSV before pregnancy, and you're just having a flare, your provider will note it in your chart and likely monitor you a bit more closely. They may also offer antiviral therapy earlier than 36 weeks if you're having frequent or severe outbreaks.
The good news: herpes doesn’t typically cross the placenta. In utero transmission is rare. It’s almost always during birth that babies are exposed. So if you’ve had an outbreak early on, you and your provider still have time to plan, treat, and prepare for a safe delivery.
Protecting Your Baby: What You Can Do
Even though herpes is a lifelong virus, it doesn’t have to define your pregnancy. You can do a lot to reduce risk:
First, if you don’t know your herpes status and your partner has a history of HSV, ask your provider about testing. Many first-time infections happen during pregnancy , sometimes in people who didn’t even know they were exposed.
If you do have herpes, stay alert to symptoms, especially in the last month. Even a tingling or subtle itch might mean the virus is active. Suppressive therapy can help minimize that risk, and it’s both safe and effective.
Talk openly with your provider about your plan for delivery. Bring up your concerns. Ask: what’s the protocol if I go into labor with symptoms? What happens if I break my water early?
Finally, after birth, avoid letting anyone with a cold sore kiss your baby. Postnatal herpes , from a well-meaning aunt or uncle , is a real risk too. Most neonatal herpes cases are preventable. Awareness is power.
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FAQs
1. Do I have to get a C-section if I have herpes?
Not necessarily. If you don’t have any visible sores or that telltale tingling when labor starts, many doctors are comfortable with vaginal birth. It’s only when herpes is clearly active that a C-section is usually recommended , it’s about protection, not punishment.
2. Can my baby get herpes from me during delivery?
Yes, but it’s rare , especially if you’ve had herpes for a while and aren’t having an outbreak when labor begins. The highest risk is with a brand-new infection in the last few weeks of pregnancy. That’s why timing and testing really matter.
3. I had a cold sore while pregnant , should I be worried?
Cold sores are usually HSV-1, and unless you're engaging in oral-genital contact during pregnancy (yes, it happens), they don’t usually pose a risk to your baby. That said, avoid kissing newborns while a cold sore is active , that’s how postnatal transmission can happen.
4. What if I’ve had herpes for years and never had symptoms during pregnancy?
That’s actually the most reassuring scenario. Your immune system is already familiar with the virus. Even if shedding happens, the risk to your baby is extremely low , especially with antiviral therapy near delivery. You’ve got this.
5. Is herpes why I had a miscarriage?
Probably not. While a primary herpes infection in the first trimester has been linked to a slightly higher risk of complications, most miscarriages have nothing to do with HSV. Still, always tell your provider , they’ll help you rule out what matters.
6. Will antivirals mess up my baby’s development?
Nope. Acyclovir and valacyclovir are two of the most studied medications in pregnancy, and research shows they’re safe. Thousands of parents have taken them with no impact on the baby’s health. If anything, they lower the risk of transmission.
7. What if my partner has herpes and I don’t?
Now’s the time to have that conversation , and probably a test. Most adult HSV transmission is actually from partners who didn’t know they had it. If your partner has it, consider avoiding sex or using protection during the last trimester. Suppression therapy might be an option for them, too.
8. Can herpes show up even if I’ve never had symptoms?
Absolutely. Most people with herpes don’t know they have it. You can shed virus without visible sores. That’s why some OBs do late-pregnancy swabs, even if you feel fine. Better safe than surprised.
9. Is it dangerous if I get herpes in the third trimester?
This is where the warning signs start to show. It's more dangerous to get a new infection this late in the game because your body hasn't had time to make antibodies to protect your baby. If this happens, your doctor will probably tell you to start taking antivirals right away and may even schedule a C-section if you are close to giving birth.
10. Can my baby go home with me if I had herpes during pregnancy?
In most cases, yes. Unless there's a known exposure or signs of infection in your baby, discharge usually happens like normal. But if there’s any concern, your little one may be monitored longer or started on antivirals as a precaution. It's scary, but early treatment works.
You're Not Alone , And You Have Options
Finding out you have herpes during pregnancy can feel like a gut punch. But you are not powerless. There are clear, evidence-based steps you and your provider can take to protect your baby and make delivery safer.
Whether it’s your first outbreak or your tenth, what matters most is communication and preparation. The right plan , testing, suppression, monitoring , works. You deserve a birth story that ends in calm, not crisis.
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How We Sourced This Article: We combined current guidance from leading medical organizations with peer-reviewed research and lived-experience reporting to make this guide practical, compassionate, and accurate. In total, around fifteen references informed the writing; below, we’ve highlighted some of the most relevant and reader-friendly sources.
Sources
1. ACOG: Management of Genital Herpes in Pregnancy
3. CDC Herpes
4. Virology Journal: Neonatal Herpes Risk by Timing of Infection
About the Author
Dr. F. David, MD is a board-certified infectious disease specialist focused on STI prevention, diagnosis, and treatment. He blends clinical precision with a no-nonsense, sex-positive approach and is committed to expanding access for readers in both urban and off-grid settings.
Reviewed by: Dr. Tara Meeks, OB/GYN | Last medically reviewed: October 2025
This article is for informational purposes and does not replace medical advice.
