Newborn infants can become infected with HSV:

• In the uterus (this is unusual)
• Passing through the birth canal (birth-acquired HSV, the most common method of infection)
• Right after birth (postpartum) from being kissed or having other contact with someone who has cold sores (oral HSV)

If the mother has an active outbreak of genital herpes at the time of delivery, the baby is more likely to become infected during birth. Some mothers may not know they have HSV sores inside the vagina.

Some women have had HSV infections in the past, but are not aware of it, and may pass the virus to their baby.

HSV type 2 (the most common cause of genital herpes) is the most common cause of HSV infection in newborn babies. However, HSV type 1 (the most common cause of oral herpes) can also occur.

Herpes may only appear as a skin infection. Small, fluid-filled blisters (vesicles) may appear. These blisters break, crust over, and finally heal. A mild scar may remain.

HSV infection may also spread throughout the body. This is called disseminated herpes. In this type, HSV can affect many parts of the body.

• Herpes infection in the brain is called herpes encephalitis
• The liver, lungs, and kidneys may also be involved
• There may or may not be blisters on the skin

Newborn infants with HSV that has spread to the brain or other parts of the body are often very sick. Symptoms include:

• Skin sores, fluid-filled blisters
• Bleeding easily
• Breathing difficulties such as rapid breathing and short periods without breathing, which can lead to nostril flaring, grunting, or blue appearance
• Yellow skin and whites of the eyes
• Weakness
• Low body temperature (hypothermia)
• Poor feeding
• Seizures, shock, or coma

HSV that is caught shortly after birth has symptoms similar to those of birth-acquired herpes.

HSV the baby gets in the uterus can cause:

• Eye disease, such as inflammation of the retina (chorioretinitis)
• Severe brain damage
• Skin sores (lesions)

Tests for birth-acquired HSV include:

• Checking for the virus by scraping from vesicle or vesicle culture
• Electroencephalogram (EEG)
• MRI of the head
• Spinal fluid culture

Additional tests that may be done if the baby is very sick include:

• Blood gas analysis
• Coagulation studies (PT, PTT)
• Complete blood count (CBC)
• Electrolyte measurements
• Tests of liver function

It is important to tell your health care provider at your first prenatal visit if you have a history of genital herpes.

• If you have frequent herpes outbreaks, you'll be given a medicine to take during the last month of pregnancy to treat the HSV. This helps prevent an outbreak at the time of delivery.
• Cesarean birth (C-section) is recommended for pregnant women who have an active outbreak of herpes sores and are in labor.
• You may have some prodromal symptoms before a sore appears. You may experience itching in the affected area, tingling or pinching sensations, muscle tenderness, shooting pains in the buttocks, legs, or groin, and nerve pain in the leg. Be sure to notify your provider if you are having these sensations.
• For women with a first-episode genital herpes infection during the third trimester of pregnancy, C-section may be offered due to the possibility of prolonged viral shedding.

HSV infection in infants is generally treated with antiviral medicine given through a vein (intravenous). The baby may need to be on the medicine for several weeks.

Treatment may also be needed for the effects of HSV infection, such as shock or seizures. Because these babies are very ill, treatment is often done in the hospital intensive care unit.

Infants with systemic HSV or HSV encephalitis often do poorly. This is despite antiviral medicines and early treatment.

In infants with skin disease, the vesicles may keep coming back, even after treatment is finished.

Affected children may have developmental delay and learning disabilities.

If your baby has any symptoms of birth-acquired herpes, including skin blisters with no other symptoms, have the baby seen by your provider right away.

Practicing safe sex can help prevent the mother from getting genital herpes.

People with cold sores should not come in contact with newborn infants. To prevent transmitting the virus, caregivers who have a cold sore should wear a mask and wash their hands carefully before coming in contact with an infant.

Mothers should speak to their providers about the best way to minimize the risk of transmitting herpes to their infant.

HSV; Congenital herpes; Herpes - congenital; Birth-acquired herpes; Herpes during pregnancy

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Kimberlin DW, Baley J; Guidance on management of asymptomatic neonates born to women with active genital herpes lesions. In: Neonatal Care: A Compendium of AAP Clinical Practice Guidelines and Policies. 2nd ed. March 2023.

Nielsen-Saines K, Cambou MC. Maternal and fetal viral infections. In: Lockwood CJ, Copel JA, Dugoff L, et al., eds. Creasy and Resnik's Maternal-Fetal Medicine. 9th ed. Philadelphia, PA: Elsevier; 2023:chap 49.

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Updated by: John D. Jacobson, MD, Professor Emeritus, Department of Obstetrics and Gynecology, Loma Linda University School of Medicine, Loma Linda, CA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.