Expert Commentary

Acyclovir to prevent neonatal herpes transmission

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Does acyclovir prevent recurrent genital herpes and viral shedding in late pregnancy?

Past studies

These have shown acyclovir’s effectiveness in decreasing the viral load present in active lesions, thereby reducing the transmission rate. In addition, continuous acyclovir in the last 4 weeks of pregnancy may prevent recurrence at term and the need for cesarean delivery.

This study

This randomized trial from Paris assessed the efficacy of acyclovir in suppressing recurrent genital herpes simplex virus (HSV) in gravidas, reducing the need for cesarean delivery to prevent neonatal infection. Of the 288 women who presented during pregnancy with active genital HSV, 167 received acyclovir orally in a dose of 200 mg given 4 times daily from 36 weeks’ gestation to term. The other 121 participants received no treatment.

At the time of delivery, all women were examined for herpes lesions, and viral cultures were obtained from the vagina and cervix. Among the 167 patients treated with acyclovir, there were no cesarean deliveries due to genital HSV, whereas in the 121 untreated women, there were 15 cesarean deliveries. No infants developed HSV infection.

The authors concluded that acyclovir treatment beginning at 36 weeks’ gestation for women who have recurrent genital HSV infection in pregnancy reduces the incidence of cesarean deliveries and viral transmission.

Find this study

Braig et al, May 2001 issue of European Journal of Obstetrics, Gynecology, and Reproductive Biology; abstract online at

Who may be affected by these findings?

Gravidas with genital HSV infection.

Expert commentary

At present, cesarean section is the preferred mode of delivery to prevent neonatal herpes transmission. However, administering antiviral therapy to gravidas may be a better management option. Unfortunately, none of the antiherpetic medications, including acyclovir, valacyclovir, and famciclovir, are approved by the Food and Drug Administration (FDA) for use in pregnancy. This study and others have clarified the need to revise the current recommendations for managing gravidas infected with HSV. Until then, all pregnant women should be screened for genital herpes during labor. Also, internal fetal monitoring should be used with caution in patients with a history of genital HSV, as local neonatal infection may occur when utilizing the fetal scalp electrode.

Unfortunately, this study does not address the problem of infants who have asymptomatic mothers but develop HSV infection anyway, nor does it examine preventive methods during pregnancy. In order to achieve a significant reduction in neonatal HSV infection in the United States, universal screening during pregnancy for HSV antibodies, along with antenatal use of antiviral prophylaxis may be the next step. Universal screening for HSV requires the availability of reliable serology tests that distinguish between HSV-1 and HSV-2. Intervention methods then could be better aimed at these populations.

The bottom line

While there is no possibility of completely eliminating the sporadic occurrence of neonatal herpes transmission, administering acyclovir to women with genital HSV infection at 36 weeks’ gestation may greatly reduce the need for cesarean delivery and the incidence of viral transmission. In addition, antiviral treatment at term of all pregnant women with a history of HSV would save $183 per patient. On a national level, this amounts to $36.6 million annually.1

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