Herpes and Pregnancy

Many women with herpes worry about the dangers it can cause to newborns. Women with herpes who are pregnant or plan on getting pregnant should not be overly alarmed. The great majority do not transmit it to their babies. However, herpes does create a special set of concerns for newborns. Transmission to newborns can cause serious problems, including herpetic viremia, herpetic meningitis, chronic skin infection or even death.

Neonatal herpes is a rare occurrence considering the large percentage of women with genital herpes. It is not a reportable disease in many states, so accurate nationwide statistics are not available. However, with the 20-25% of American women with genital herpes, the incidence of neonatal herpes is estimated to be around 0.1%.

How It Is Transmitted To Infants
In about 90% of neonatal herpes cases, the newborn contracts HSV-1 or 2 on its way through the birth canal. If an outbreak is present, the rate of transmission is high because of the high risk of viral shedding at that time. It is also possible for an infant to become infected through asymptomatic shedding, though this is much less common.

If a woman has had a long-standing herpes infection, the baby gets some protection from the placenta, which provides antibodies from her blood. Even if there is some viral shedding present during delivery, the infant has some defense against transmission. Women who contract herpes during their first and second trimesters usually have enough time to develop some antibodies that help protect the fetus. Babies who are born prematurely are at a higher risk of contracting the virus, even in mothers with long-standing infections, because it takes about 28 weeks for the antibodies to start transferring to the baby.

The risk is higher for women who contract herpes during the last trimester of pregnancy, as there is not enough time for an antibody defense to build up. In addition, people with new herpes infections have a higher rate of asymptomatic shedding for the first year after contracting the virus. It is thought possible that up to 50% of neonatal herpes cases occur when the mother has her primary herpes infection within several weeks of delivery. If a mother has a primary outbreak during pregnancy, there is also a small chance that the virus can cross the placenta and infect the baby.

What Expectant Parents Can Do
If you know you have herpes it is important to tell your obstetrician or midwife about your condition so it can be monitored throughout your pregnancy. Some studies show that many cases of neonatal herpes occur in instances where the mother is not aware she carries the virus. In these cases, neither the doctor nor the mother is on the lookout for sores or other herpes symptoms.