What Is Neonatal Herpes? And How Can It Affect Your Newborn

Parent kissing their newborn baby

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Neonatal herpes is a viral infection caused by the herpes simplex virus (HSV). Though relatively rare, neonatal herpes can be incredibly harmful to a newborn’s fragile health.

In adulthood, HSV can cause cold sores on the mouth, blistering on the genitals, and lesions elsewhere on the body. HSV can be transmitted to a newborn through skin-to-skin contact, resulting in neonatal herpes. If the birthing parent has an outbreak of HSV on the genitals at the time of delivery, this transmission can occur at birth. Less commonly, a newborn can also contract neonatal herpes if someone with a cold sore kisses them.

Here we outline what neonatal herpes is, how it can be transmitted and what you can do if you think your baby is at risk of contracting it.

What Is Neonatal Herpes?

In adulthood, HSV can cause painful blistering, sores, or a rash that heals once the outbreak is over. Neonatal herpes is a herpes virus infection of a newborn baby and is estimated to affect 1 in 3,200 live births in the US.

Similar to adults, neonatal herpes can cause blistering of the skin around the eyes, mouth, and occasionally the scalp. However, due to their undeveloped immune systems, neonatal herpes can also cause damage to a newborn’s organs and central nervous system.

“This can be a life-threatening disease,” explains Jeffrey Kahn, MD, PhD, director of pediatric infectious disease at UT Southwestern Medical Center and the director of infectious diseases at Children’s Medical Center. “If the virus gets into the central nervous system it can be devastating.” 

Neonatal herpes can also escalate into other serious viral infections, such as meningitis and encephalitis, which is an inflammation of the brain tissue. It can also be disseminated, which means that it spreads throughout the entire body. “Those kids [become] very ill,” explains Janet Soul, MD, director of the fetal-neonatal neurology program at Boston Children’s Hospital.

Not all babies that contract neonatal herpes will become severely ill, but there are certain factors that can increase the risk to the infant.

Who Is at Risk for Neonatal Herpes?

Many pregnant parents-to-be who have HSV have developed an immune response to the virus over time. These antibodies are passed on to their unborn child during pregnancy, potentially giving them a certain layer of protection against neonatal herpes. 

However, contracting HSV close to the delivery date can be harmful to an unborn baby, as no immune response has had time to develop or pass on. These babies are at a heightened risk of contracting neonatal herpes and becoming severely ill as a result, regardless of what strand of the disease they have had contact with.

“Probably the most important factor here is whether the mother has antibodies or an immune response to [either strand] of the herpes virus,” explains Dr. Kahn. “If the infant is acquiring it from the mother, she most likely has antibodies that she passed on to the infant during pregnancy that may protect the infant. The exception would be if the herpes virus infection in the mother is acquired very close to the time of delivery, such that the mother’s body or immune system doesn’t have time to develop an antibiotic response.”

All newborns have an undeveloped immune system, leaving them at risk of contracting viruses. However, those suffering from immunodeficiency, such as premature infants, are at a greater risk of suffering adverse effects of neonatal herpes.

How Is Neonatal Herpes Spread?

There are two types of herpes virus: HSV-1 is more commonly known as oral herpes and HSV-2 is more commonly known as genital herpes. However, both strands of HSV can cause an outbreak anywhere on the body and both strands can be transmitted to a newborn, resulting in neonatal herpes. 

The most common cause of transmission of HSV to a newborn is during childbirth when the infant comes into contact with active herpes lesions on their parent's genitals during delivery. If you, like the estimated 22% of people who have HSV-2 during pregnancy, have active herpes lesions at the point of delivery, your obstetrician may suggest a cesarian section to avoid transmission to your infant.

The HSV virus can also be spread to a newborn via contact with an active herpes outbreak on any part of the body, such as on the breast or nipple (which the infant may come into contact with during feeding) or via contact with a cold sore on the lip. If someone has a cold sore and kisses the infant, they can also inadvertently transmit the virus.

Transmission of HSV can occur even if someone touches or scratches their cold sore and then touches the baby. “If anyone has a cold sore, [do] not touch the baby and certainly [do] not kiss the baby,” urges Dr. Kahn. “If somebody has a cold sore and they scratched the cold sore and then touched the baby, then they’re unknowingly transmitting the virus.”

Jeffrey Kahn, MD, PhD

If anyone has a cold sore, [do] not touch the baby and certainly [do] not kiss the baby.

— Jeffrey Kahn, MD, PhD

What Are the Symptoms of Neonatal Herpes?

An infant with neonatal herpes may display symptoms as early as two days and as late as sixweeks after exposure to the virus. However, for an infant who contracted neonatal herpes during childbirth, symptoms typically appear within seven to 10 days of delivery.

"There are a couple of ways that these infants will present; one is a blistering rash and it could be very focal," says Dr. Kahn. This rash or small crop of blisters might appear on the scalp, around the umbilical stump, or any area of broken skin.

Perhaps confusingly for parents and caregivers, neonatal herpes can be present even without the tell-tale rash or blisters. "The second way is that the children get quite sick and it becomes pretty obvious to the parent that the baby is not acting well, not feeding, or not responsive," explains Dr. Kahn. A fever or a very low temperature and lethargy are other potential indicators.

"A more specific neurological symptom would be seizures," says Dr. Soul. Seizures suggest that the virus has made its way into the central nervous system. "That, by definition, means that some of the brain cells are going to be injured. Then it’s just a question of how much."

What Do I Do If My Child Has Neonatal Herpes?

Not all newborns that contract neonatal herpes will become seriously ill, but many of them do. It is important to pay close attention to any potential symptoms. Don't dismiss a rash as a bacterial infection when it could be a sign of neonatal herpes, urges Dr. Kahn. Additionally, if you have HSV in pregnancy, particularly if you contracted it close to your due date, raise this with your child's pediatrician and your OB/GYN.

"It’s a rapidly progressive infection and in many cases, by the time the child is brought to medical care, the infection has been going on for quite some time and there’s already consequences of the infection present," says Dr. Kahn.

A blistering rash, lethargy, or not feeding well are all indications that your newborn needs urgent medical attention. Abnormal movements should also be cause for concern. "The vast majority of parents out there have never seen a seizure in a neonate, but if there are movements that seem to be unusual, definitely bring them in," says Dr. Kahn.

If your baby's pediatrician suspects that neonatal herpes is present, they will likely administer an IV drip of medication, including antibiotics, acyclovir, and anti-seizure medication to help stem the spread of the virus.

A Word From Verywell

Contracting neonatal herpes can be incredibly harmful to a newborn’s health. However, there is plenty you can do to mitigate any risk to your infant, even if you are a carrier of the HSV virus. 

Stay vigilant to any active HSV outbreaks during pregnancy and discuss them with your healthcare provider ahead of delivery. Additionally, raise the risk of neonatal herpes to your friends and family and ask them to wash their hands thoroughly before holding your infant and to refrain from kissing them. As well as neonatal herpes, this will help protect your newborn against any potentially harmful viruses.

12 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Nicola Appleton
Nicola Appleton is a UK-based freelance journalist with a special interest in parenting, pregnancy, and women's lifestyle. She has extensive experience creating editorial and commercial content for print, digital, and social platforms across a number of prominent British and international brands including The Independent, Refinery29, The Sydney Morning Herald, HuffPost, Stylist, Canva, and more