Herpes virus infection in pregnant woman


Herpesviridae family is a big group of DNA-containing viruses that cause a wide range of disorders and symptoms. Herpes simplex virus (HSV) is probably one of the most common infections observed in humans – with higher prevalence of HSV-1 (about 80% to 30%). Specific property of this infection is their long-lasting and even lifelong course, as it tends to establish latent, asymptomatic infection with periodic reactivation. Therefore, pregnant women may even have no idea that she is infected, the same applies to their sexual partners. Herpes virus infection in pregnant woman may be dangerous for a child, although typically mother’s immune reaction is potent enough to protect the fetus.

Herpes virus

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The virus

Herpes simplex viruses belong to the alpha herpesvirus group. HSV possesses an internal core with a linear double-stranded DNA. The capsid of herpes viruses consists of 162 consumers. The virus is wrapped in a lipid envelope with viral glycoproteins on the surface. Its molecular weight is approximately 100×106 units and diameter of approximately 160 nm. Two types of the HSV are distinguished. HSV-1 is associated with oral herpes, whereas HSV-2 is known to cause genital herpes, although both types may affect almost every part of the body. And each virus can be transmitted to the fetus or a newborn baby.

HSV infection

Herpes virus infection in pregnant woman may affect the fetus and cause inborn infection with some serious and sometimes life-threatening complications. However, luckily neonatal herpes infection is relatively rare despite higher infection rates among pregnant women. Still HSV-1 is more likely to be transmitted to a child than HSV-2.

Nevertheless, the baby is more likely to get infected if a mother catches the infection during the pregnancy (primary infection, especially acquired in the late stages of pregnancy) due to low amount of the antibodies against HSV. In case of newly-acquired infection the virus can spread to the virus via the placenta  and umbilical cord (so-called antenatal contraction of the virus when the infection is acquired prior to the delivery). Alternatively, those women who acquired the infection before that period of time rarely transmit the infection to their children. The infection acquired through placenta may affect the skin, cause chorioretinitis (inflammation of the vessels and retina), microcephaly (small head and decreased brain volume), hydrocephaly (abnormal fluid production in the ventricles of the brain) and/or microphtalmia (abnormally small eyes). If a woman contracts the infection on the first trimester may cause stillbirth or spontaneous abortion, whereas primary infection in the third trimester is associated with preterm labor and/or intrauterine growth restriction.

The most common transmission route is a so-called intrapartum transmission which occurs during the delivery when a baby is pushed through the infected birth canal.

Postnatal transmission occurs during the first weeks of baby’s life when an infected mother/relative or even healthcare worker touches or kisses a child (however, it is quite rare).

Knowing about the infection a woman can take measures to minimize the risks and make sure that a newborn baby will be healthy.

Herpes virus infection in pregnant woman: Neonatal herpes

HSV infection in newborn babies (younger than 6 weeks) may manifest as:

  • Localized infection of the skin (with vesicular rash), eye, and/or mouth (SEM) observed in up to 45% of infected babies;
  • Brain infection (encephalitis) with or without the involvement of the skin, eyes and mouth;
  • Disseminated infection with multiple organ involvement (brain, lungs, skin, liver, adrenal etc.);

HSV diagnosis and treatment in pregnancy

Primary herpes virus infection in pregnant woman should be treated with antiviral medications such as acyclovir and valacyclovir given orally or intravenously (in case of serious or disseminated infection) for 7-10 days.

Women who have recurrent genital herpes and who were infected and treated in the first/second trimester should receive antiviral medications from the 36th week of pregnancy until delivery.

Herpes virus infection in pregnant woman: Prevention

  • It is recommended to check for HSV infection early in pregnancy with repeated testing at 32 to 34 weeks of pregnancy if a woman has had a partner with genital HSV;
  • Cesarean delivery should be considered for women with active and/or primary HSV infection in late stages of pregnancy (especially within 6 weeks prior to the due date) with lesions of the birth canal;
  • If the spontaneous rupture of the membranes occurs in the infected/ill woman, C-section should be performed as soon as possible (recommended within 4 hours);
  • Fetal scalp electrode usage should be avoided during the delivery in infected woman;