Can Herpes Cause Miscarriage or Later Pregnancy Loss?

Learn How You Can Protect Your Baby from the Risks of Herpes

pregnant woman and doctor
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If you've been diagnosed with herpes you might wonder if it can cause miscarriage or later pregnancy loss. While some research has linked herpes simplex virus to miscarriage, the biggest risk of active herpes during pregnancy is that the baby could become infected during birth.

What Is Herpes?

Herpes simplex virus, or HSV, is a virus that can cause sores and blisters in either the mouth or the genital area (and occasionally other body parts).

As background, there are two main forms of herpes, HSV-1 and HSV-2. Doctors used to think that HSV-1 caused only cold sores (oral herpes) and HSV-2 genital herpes, but they now know that both virus types can cause both types of herpes.

Herpes is very common. Between 50 and 80 percent of all adults carry oral HSV and about 1 in 4 have a genital HSV infection, although it may be inactive. Most people who are infected are not aware of it, because many people rarely or never develop the characteristic blisters. HSV cannot be cured, although it can be controlled and may become dormant.

Herpes and Miscarriage Risk

Despite HSV being a very common infection, doctors don't believe that the virus causes miscarriages in most cases.

Some research shows that women with unexplained recurrent miscarriages are more likely to have an undetected HSV infection than women with no history of miscarriage. However, it's unknown if the virus actually plays a role in causing miscarriages for those women.

Most women who are infected with HSV do not have recurrent miscarriages, so doctors need to conduct more research on the matter.

Similarly, a few researchers have found evidence that the virus could cross the placenta and lead to damage of the placenta, potentially increasing the risk of late pregnancy loss.

Doctors don't understand what factors cause this to happen, given that the majority of infected women do not have this problem.

Mother-to-Child Infection

The biggest risk of having an active genital herpes infection during pregnancy is that the baby could acquire the infection during delivery, which could lead to serious health complications or death.

Doctors may suggest a c-section for women with active herpes who are about to give birth, and they may prescribe an antiviral medications called Zovirax Injection (acyclovir) to women with a history of genital herpes infection in order to prevent an outbreak near the time of delivery. This medication is safe for your developing baby. 

The risk of the baby being infected at birth is much higher for pregnant women who acquire genital herpes for the first time in their third trimester of pregnancy than for women who have been previously infected. It's therefore important to continue to practice safe sex during pregnancy. Fewer than 1 percent of women who acquired herpes before they were pregnant or in the first half of their pregnancy will pass it to their baby.


If you are concerned by what you suspect are herpes symptoms, the best thing to do is to talk to your OB/GYN or midwife about your concerns. Merely having a history of herpes, however, shouldn't keep you from having a healthy pregnancy if you follow your doctor's advice. 


Genital HSV Infections. Centers for Disease Control and Prevention. June 8, 2015.

Avgil, M. and Ornoy, A. (2006). Herpes simplex virus and Epstein-Barr virus infections in pregnancy : consequences of neonatal or intrauterine infection. Reproductive Toxicology.

Genital Herpes and Pregnancy. March of Dimes. March 2005. 

Naib, Z.M., Nahmias, A.J., Josey, W.E., et al. (1970). Association of Maternal Genital Herpetic Infection with Spontaneous Abortion. Obstetrics & Gynecology.

Herpes Simplex Virus in the Newborn. New York State Department of Health. June 2006. 

Management of Genital Herpes in Pregnancy. Green-top Guideline No. 30. Royal College of Obstetricians and Gynecologists. September 2007. 

Zaki, M.E. and Goda, H. (2007). Relevance of Parvovirus B19, Herpes Simplex Virus 2, and Cytomegalovirus Virologic Markers in Maternal Serum for Diagnosis of Unexplained Recurrent Abortions. Archives of Pathology & Laboratory Medicine.

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