What You Need to Know: The Dangerous Impact of Herpes Simplex Virus (HSV) During Childbirth

The herpes simplex virus (HSV) can cause devastating complications for infected newborns whose mothers have genital herpes. Understanding risk and research can help you, and your baby, when the time comes.

In the US, about one out of six people aged 14 to 49 have genital herpes. According to the Centers for Disease Control and Prevention (CDC), there are more than 776,000 new cases each year — that is a lot. While many people think you can only get genital herpes from someone with an open sore, that's not true, so don't believe it. You can catch genital herpes from virus shed onto perfectly healthy looking skin and mucous of the mouth, rectum, and vagina. Genital herpes is also readily transmitted by those who are unaware they are even infected.

Babies born to infected women can suffer permanent disability, or death if they contract the virus during the birth process.

So What Is Genital Herpes?

Genital herpes is a common sexually-transmitted disease caused by herpes simplex viruses. HSV-1 typically causes cold sores in children and older adults, while HSV-2 is more likely to result in genital ulcers called "genital herpes." Either type of HSV can cause genital herpes, and the Centers for Disease Control and Prevention (CDC) notes more people are getting genital herpes via HSV-1. This change seems to be due to fewer people contracting HSV-1 as children from family through everyday contact. While that sounds like a good thing, it could mean children are more susceptible to the transmission of HSV-1 through oral sex when they are older — leaving them with genital herpes.

After infection, symptoms usually occur within four to 12 days. The symptoms accompanying the first outbreak can be worse than subsequent herpes events. Initial troubles include longer-lasting lesions, body pain, fever, swollen lymph nodes, and fatigue.

While there is no standard vaccine yet and no cure for HSV, it is a manageable condition that requires education, sharing of information with sexual partners, and use of protective condoms during sex. Ulcers caused by genital herpes can increase the risk of transmission of HIV. For most, HSV is a lifelong infection that remains dormant in nerve cells, or not.

The Dangers of HSV and Pregnancy

Genital herpes transmits more easily from infected male to uninfected female during penile-vaginal sex. For pregnant women, infection with genital herpes can cause serious complications. The virus can pass from mother to child, usually during its journey through the birth canal, resulting in a condition called "neonatal herpes."

The chances of a woman, who is experiencing an initial outbreak of genital herpes during the third trimester of pregnancy, of passing the infection to her child are about 33 percent. Neonatal herpes can cause microcephaly, infection of the central nervous system, and lesions of the skin, mouth, or eyes, encephalitis, permanent disability, or death of the baby. Doctors sometimes recommend caesarean delivery for women experiencing initial infectious response to a genital herpes infection during pregnancy.

The rate of neonatal HSV infection is about one in every three to 10,000 births. Even when treated with antiviral medications, the infection can cause significant damage and death to its newborn victims. Recently, a research team looked at how antibodies made by mom, after an HSV-1 infection, may help protect unborn babies from the life-threatening consequences of infection.

Maternal Antibodies Could Help Prevent Dangerous HSV Infections in Babies

In a study published in the journal mBio, scientists from Dartmouth University used mouse studies to investigate if HSV antibodies made after infection with genital herpes could protect unborn children or babies exposed to HSV at birth.

To reduce the rate of neonatal infections, researchers explored the use of maternal antibodies to prevent HSV infection in mice and evaluated the diffusion of maternal antibodies to HSV in samples of human neural tissue. Using six to ten-week-old mice, the scientists came to an important finding — that the antibodies already present in a pregnant woman with HSV-1 likely have an immunizing effect on their unborn children, potentially protecting them against serious complications of infection with HSV-1.

David Leib, professor of microbiology and immunology at the Geisel School of Medicine notes in a press release:

What this tells us is that women who get pregnant who have a pre-existing herpes infection have a mature immune response to that virus and will pass those antibodies to their baby. If that baby should be infected during delivery, it will be protected because the mother's antibodies get into its nervous system before birth.

The researchers report the movement of maternal antibodies into fetal neural tissue "was almost overlooked but helps explain a decades-old finding that showed antibodies attenuating the neural spread of HSV-1." Note that they've only studied HSV-1 in this capacity, the researchers don't know if the same mechanisms are at play in the maternal-to-fetal transmission of HSV-2.

While no successful vaccine has been developed to protect adult to adult transmission of any HSV virus, this research offers a potential pathway to immunize at-risk mothers to help their children. The study also suggests that maternal immunization may prove potent for protecting newborns from the impacts of viruses like Zika, given that maternal antibodies can cross into fetal neural tissue.

If you are pregnant and know you have been exposed to, or experienced, genital herpes, talk to your doctor about the best plan for you. If your partner has herpes, be sure to use a condom during intercourse, every time, not just when symptoms are present.

This study offers knowledge of how our bodies innately protect our children — but may also prove to be a stepping stone towards protecting future generations from the ravages of emerging infectious diseases like Zika.

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