How is fetal transmission of herpes simplex virus (HSV) infection prevented?

Updated: Mar 17, 2020
  • Author: Sean P McGregor, DO, PharmD; Chief Editor: William D James, MD  more...
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Women who are HSV-2 negative should be counseled to abstain from intercourse during the third trimester of pregnancy with partners who could be seropositive because primary HSV infection during this time places the fetus at highest risk of infection.

The most common approach in attempting to prevent vertical transmission is to have women with clinically apparent HSV lesions during labor undergo cesarean delivery. However, cesarean delivery does not prevent all cases of neonatal infection because in utero infection occurs and antepartum HSV cultures are not a good predictor of neonatal infections.

Use of acyclovir 400 mg PO thrice daily during the third trimester of pregnancy has been proven to be safe and effective in preventing neonatal herpes and in eliminating the need for cesarean deliveries. [79]

A large nationwide cohort study in Denmark did not find any association between first trimester in utero antiviral drug (ie, acyclovir, valacyclovir, famciclovir) exposure and congenital anomalies. In 1804 pregnancies exposed to an antiviral drug during the first trimester, 40 infants (2.2%) were diagnosed with a major birth defect, compared with 19,920 (2.4%) unexposed pregnancies. [80] A 2017 review also reports that prophylactic acyclovir reduces active genital lesions at delivery. [81]

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