What is the relationship between genital herpes (Herpes Simplex Virus, HSV) and pregnancy?

From the Guidelines

Genital herpes during pregnancy requires careful management to protect both the mother and baby, and suppressive therapy with acyclovir (400 mg TID) or valacyclovir (500 mg BID) starting at 36 weeks’ gestational age is recommended for women with a history of genital herpes to reduce the risk of viral shedding, recurrences, and cesarean deliveries. If you have genital herpes and are pregnant, inform your healthcare provider immediately. For active outbreaks, acyclovir (400mg three times daily), valacyclovir (500mg twice daily), or famciclovir (250mg three times daily) are generally considered safe during pregnancy, as acyclovir remains category B 1. Some key considerations for managing genital herpes during pregnancy include:

• Women with a history of genital herpes should be assessed at 36 weeks of pregnancy, and those with recurrent herpes may receive antiviral suppressive therapy starting at 36 weeks to reduce the risk of an outbreak during delivery 1.
• If active lesions are present at the time of delivery, a cesarean section is typically recommended to prevent transmission to the baby during vaginal birth, as neonatal herpes can cause serious complications including neurological damage.
• Regular prenatal care is essential, and you should report any symptoms such as tingling, burning, or visible sores to your healthcare provider immediately.
• The greatest risk to the baby occurs when a mother acquires a primary herpes infection late in pregnancy, so partners should be tested and use protection if their status is unknown or positive. It is also important to note that routine screening of pregnant women for HSV serostatus is not recommended due to a lack of evidence for cost-effectiveness 1.

From the FDA Drug Label

Clinical data over several decades with valacyclovir and its metabolite, acyclovir, in pregnant women, have not identified a drug associated risk of major birth defects. The risk of neonatal HSV infection varies from 30% to 50% for genital HSV acquired in late pregnancy (third trimester), whereas with HSV acquisition in early pregnancy, the risk of neonatal infection is about 1% A primary herpes occurrence during the first trimester of pregnancy has been associated with neonatal chorioretinitis, microcephaly, and, in rare cases, skin lesions.

The use of valacyclovir during pregnancy has not been directly associated with a risk of major birth defects. However, there are risks to the fetus associated with untreated herpes simplex during pregnancy, including neonatal HSV infection, which can occur in 30% to 50% of cases if acquired in late pregnancy. Key considerations for genital herpes and pregnancy include:

• The risk of neonatal infection is higher if genital HSV is acquired in late pregnancy
• Primary herpes occurrence during the first trimester can be associated with rare but serious outcomes, such as neonatal chorioretinitis and microcephaly
• The background risk of major birth defects and miscarriage in clinically recognized pregnancies is estimated to be 2% to 4% and 15% to 20%, respectively 2

From the Research

Genital Herpes and Pregnancies

• Genital herpes is a common viral sexually transmitted disease that can be transmitted to the fetus or neonate during pregnancy, with a risk of neonatal herpes around 1% 3.
• Studies have shown that antiviral prophylaxis, such as acyclovir or valacyclovir, can reduce the risk of recurrent genital herpes at delivery and the need for cesarean delivery 4, 5, 6, 7.
• A systematic review of five trials found that acyclovir prophylaxis beginning at 36 weeks' gestation was effective in reducing clinical HSV recurrences at the time of delivery, cesarean deliveries for clinical recurrence genital herpes, and the risk of HSV viral shedding at delivery 7.

Management of Pregnant Women with Recurrent Herpes

• Guidelines for clinical practice recommend that antiviral prophylaxis be offered to women with recurrent genital herpes during pregnancy from 36 weeks of gestation and until delivery 3.
• In case of recurrent genital herpes at the onset of labor, cesarean delivery should be considered, especially if the membranes are intact and/or in case of prematurity and/or in case of HIV positive woman 3.
• Vaginal delivery can be considered in case of prolonged rupture of membranes after 37 weeks of gestation in an HIV negative woman 3.

Effectiveness of Antiviral Prophylaxis

• Studies have shown that valacyclovir suppression after 36 weeks of gestation significantly reduces HSV shedding and recurrent genital herpes requiring cesarean delivery 4.
• Acyclovir prophylaxis has been shown to reduce the rate of Cesarean section, viral shedding, and recurrent genital herpes at delivery 5, 6.
• A prospective study found that acyclovir prophylaxis in late pregnancy prevents recurrent genital herpes and viral shedding, with a significant reduction in the rate of Cesarean section 6.