Pregnancy and herpes

Pregnancy and herpes is a health topic, not a disease or diagnosis. It describes how infection with herpes simplex virus, or HSV, may affect care during pregnancy, labor, and the newborn period.

HSV-1 commonly causes cold sores around the mouth, but it can also cause genital herpes. HSV-2 usually affects the genital area. Either type can be passed to a baby, although the circumstances and level of concern differ.

Herpes simplex is not the same as shingles. Shingles is caused by varicella-zoster virus, the virus that also causes chickenpox.

Most people who had genital herpes before pregnancy can expect routine prenatal care with some added planning near birth. The main concern is a genital infection acquired late in pregnancy. This matters because the body may not have had time to make protective antibodies before labor.

Tell your prenatal care team about any current or past genital herpes, even if the last outbreak was years ago. Also mention possible new exposure during pregnancy.

After the first HSV infection, the virus remains inactive inside nearby nerves. It may later become active again. This is called a recurrence or outbreak. HSV can sometimes be released from the skin without visible sores, known as asymptomatic shedding.

During pregnancy, antibodies against an infection you already have can cross the placenta to the baby. These antibodies provide some protection around birth. This is why a recurrence of long-standing genital herpes is generally less concerning than a newly acquired infection near delivery.

A “first episode” means the first recognized outbreak. It does not always mean the infection was acquired recently. A lesion swab and, in selected cases, a type-specific antibody blood test may help clarify whether an infection is new.

HSV is most often passed to a newborn during vaginal birth through contact with virus in the genital tract. Transmission before birth or from close contact after birth is less common, but it can happen.

A PCR test is usually the preferred test for an active sore. PCR stands for polymerase chain reaction. It looks for the virus’s genetic material in a swab taken from the lesion. Blood tests look for antibodies, not the virus itself, and cannot show exactly where an infection is located.

The timing and location of HSV affect pregnancy planning. Your care team will consider:

• Whether herpes is oral or genital
• Whether infection occurred before or during pregnancy
• Whether genital sores or warning sensations are present during labor
• Whether this is a first episode or a recurrence

Antiviral medicines such as acyclovir or valacyclovir may be used during pregnancy. They can shorten an outbreak and reduce viral activity. A clinician may recommend daily suppressive treatment late in pregnancy for someone with recurrent genital herpes. The timing follows local guidance and your individual history.

A vaginal birth is usually possible when there are no genital lesions or warning symptoms at the start of labor. Warning symptoms, called a prodrome, can include localized burning, pain, or tingling that usually comes before an outbreak.

Cesarean birth is generally recommended when genital lesions or prodromal symptoms are present during labor. It reduces, but does not remove, the chance of transmission to the baby. A first genital episode late in pregnancy may require a more detailed discussion about timing and method of birth.

Routine blood screening for HSV is not recommended for every pregnant person. Testing may be useful when there are active lesions, an uncertain diagnosis, or a partner with known herpes.

The most important related condition is neonatal herpes, meaning HSV infection in a newborn. It may affect the skin, eyes, or mouth. It can also affect the brain and nervous system, called herpes encephalitis, or spread through several organs, called disseminated herpes.

Neonatal herpes needs urgent hospital treatment. Early signs can be subtle, and some babies do not have visible blisters.

Congenital herpes is infection acquired before birth. It is uncommon but can affect the skin, eyes, brain, or growth of the developing baby.

A new genital HSV infection during pregnancy can cause a more noticeable first episode. Rarely, HSV spreads beyond the skin and causes serious maternal illness, including hepatitis or encephalitis.

Contact your maternity or prenatal service promptly if you develop new genital blisters, ulcers, burning, or pain during pregnancy. A swab is most useful while a fresh lesion is present.

Contact your maternity unit immediately if labor begins or your waters break while you have genital sores or prodromal symptoms. This requires prompt assessment, but it does not automatically mean the baby has been infected.

A newborn needs urgent medical assessment for blisters, unusual sleepiness, poor feeding, fever, low temperature, marked irritability, or breathing difficulty. Call emergency services if a baby has a seizure, is difficult to wake, or is struggling to breathe.

If you have a remote history of genital herpes and feel well, nothing usually needs to be done urgently. Mention it at a routine prenatal appointment so that it can be included in your pregnancy and birth plan.

Keep a record of:

• Whether previous outbreaks were oral or genital
• When the first and most recent outbreaks occurred
• Any previous HSV test results
• Antiviral medicines you have used
• Whether a current partner has oral or genital herpes

If a new lesion appears, ask whether it can be swabbed for HSV PCR. Do not rely on photographs or appearance alone, because other skin conditions can resemble herpes.

If your partner has genital or oral herpes and you do not know whether you have HSV, ask your prenatal clinician whether type-specific blood testing would help. Condoms reduce genital exposure but do not fully prevent HSV because uncovered skin may release the virus.

To reduce new exposure late in pregnancy, avoid sexual contact with an area affected by an active outbreak. Centers for Disease Control and Prevention (CDC) guidance also advises people without known genital herpes to avoid vaginal sex during the third trimester with a partner who has known or suspected genital herpes. Avoid receiving oral sex during that period from a partner with oral herpes.

After birth, anyone with a cold sore should wash their hands before touching the baby, keep the sore covered where possible, and not kiss the baby. Breastfeeding can usually continue if there are no lesions on the breast. If a lesion is on a breast or nipple, do not feed or express milk for the baby from that side until it has healed; ask your maternity or infant-feeding team for specific guidance.

Does genital herpes always mean a cesarean birth?

No. Vaginal birth is usually an option when there are no genital lesions or prodromal symptoms during labor. Active genital lesions, a warning prodrome, or a first episode late in pregnancy may change the recommendation.

Can a cold sore affect the pregnancy?

A cold sore does not usually change pregnancy care in the same way as genital herpes. After birth, however, direct contact between a cold sore and the baby can transmit HSV. Avoid kissing the baby and use careful hand hygiene until the lesion heals.

Can herpes be passed to a baby without visible sores?

Yes. HSV can sometimes be released without visible lesions. However, the risk around birth is strongly influenced by whether the infection is newly acquired, whether genital symptoms are present, and whether protective maternal antibodies already exist.

Are antiviral medicines used during pregnancy?

Yes. Acyclovir and valacyclovir are used to treat outbreaks and may be offered as suppression late in pregnancy. The choice and timing should be based on your history and local maternity guidance.

Should my baby be tested after birth?

Not every baby needs testing. Testing or observation may be recommended if genital lesions were present during labor, infection was acquired late in pregnancy, or the baby develops concerning signs. The newborn team may use swabs, blood tests, or spinal fluid testing according to the situation.

Can I breastfeed if I have genital herpes?

Usually, yes. Genital herpes does not pass through breast milk. Keep lesions covered and wash your hands before handling the baby. Do not nurse from a breast with an active herpes lesion.