Can Herpes Cause Miscarriage or Later Pregnancy Loss?

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. Worldwide, about 67% of people under the age of 50 carry oral HSV-1 and about 11% of people aged 15-49 have 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 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. 

So, it's important to continue to practice safe sex during pregnancy. Fewer than 1% of women who acquired herpes before they were pregnant or in the first half of their pregnancy and who are asymptomatic at birth will pass it on 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.