HSV is a highly prevalent viral infection caused by two types: HSV-1 and HSV-2. Both types can cause genital infection, and the virus is transmitted through direct contact with lesions, mucosal surfaces, or genital secretions. Because many women of childbearing age are infected or become infected during pregnancy, concerns about transmission to the baby are common. Healthcare providers monitor and manage HSV infection throughout prenatal care to protect the newborn.
Current Guidelines for Routine HSV Screening During Pregnancy
Routine, universal screening for Herpes Simplex Virus in all asymptomatic pregnant individuals is not recommended by major health organizations, including the Centers for Disease Control and Prevention (CDC) and the American College of Obstetricians and Gynecologists (ACOG). This guidance applies to both viral culture and blood-based antibody screening tests. The reasoning is that testing low-risk, asymptomatic individuals has not been shown to significantly improve maternal or neonatal outcomes.
Blood tests used for screening can sometimes produce false-positive results, which may cause unnecessary anxiety for the patient. The potential for unwarranted medical procedures, such as an elective Cesarean section, also weighs against routine testing when no symptoms are present. Therefore, prenatal care focuses on a targeted, symptom-driven approach rather than broad population screening.
When Targeted HSV Testing is Performed
Targeted testing is performed under specific clinical circumstances to guide management. If a pregnant person presents with active genital lesions, blisters, or ulcers suggestive of herpes, a healthcare provider will order a virologic test. This is typically done using a viral culture or a highly sensitive polymerase chain reaction (PCR) swab test to confirm the presence of the virus and determine its type (HSV-1 or HSV-2).
Testing is also considered when a pregnant individual has an asymptomatic partner with a known genital HSV infection. In this scenario, a type-specific blood test, which detects antibodies, can be used to determine the pregnant person’s serostatus. Identifying a seronegative individual allows for specific counseling on prevention strategies to avoid acquiring a primary infection during pregnancy, especially in the third trimester.
Understanding Neonatal Herpes and Risk Factors
The main concern regarding maternal HSV infection is the potential for transmission to the newborn, resulting in neonatal herpes, a rare but devastating infection. The virus is most commonly transmitted during passage through the birth canal when the baby comes into direct contact with viral shedding in the mother’s genital tract. Neonatal herpes can lead to severe long-term consequences, including central nervous system damage or death, if not promptly treated with antiviral medication.
The risk of transmission depends critically on the timing of the maternal infection. The highest risk, estimated to be between 25% and 50%, occurs when a mother acquires a primary, first-ever HSV infection late in the third trimester. This is because the mother has not had sufficient time to build and pass protective antibodies across the placenta. If the mother has a history of recurrent outbreaks, the risk of transmission is significantly lower, typically less than 2%, due to the presence of maternal antibodies offering some protection.
Preventing Transmission Near Delivery
Proactive management steps are taken in the late stages of pregnancy for individuals with a history of genital herpes to minimize transmission risk. Suppressive antiviral therapy, using medications like acyclovir or valacyclovir, is offered to women with recurrent outbreaks or a primary infection during pregnancy. This therapy usually begins at or beyond 36 weeks of gestation and continues until delivery.
The goal of late-term suppression is to reduce recurrent outbreaks and asymptomatic viral shedding at the time of labor. Reducing viral activity decreases the need for a Cesarean section. A Cesarean delivery is recommended only when a mother has active genital lesions or is experiencing prodromal symptoms, such as vulvar pain or burning, at the onset of labor. This indicates a high likelihood of viral shedding. If no active lesions are visible at the time of delivery, a vaginal birth is considered safe.