Br J Obstet Gynaecol. 1998 Mar;105(3):275-80.

A randomised placebo controlled trial of suppressive acyclovir in late pregnancy in women with recurrent genital herpes infection.
Brocklehurst P, Kinghorn G, Carney O, Helsen K, Ross E, Ellis E, Shen R, Cowan F, Mindel A.

Academic Department of Genitourinary Medicine, UCL Medical School, London.

Objectives:

To evaluate the efficacy and safety of a suppressive course of acyclovir in late pregnancy in women with recurrent genital herpes infection on the incidence of viral shedding, herpes lesion development and caesarean section for recurrent genital herpes.

Design:

Double-blind, randomised placebo controlled clinical trial.

Setting:

A department of genitourinary medicine in Sheffield and an antenatal clinic in London. POPULATION: Pregnant women with recurrent genital herpes infection at < 36 weeks of gestation.

Methods:

Participating women were given acyclovir 200 mg four times a day (or matching placebo) from 36 weeks of gestation until the time of delivery. Women were seen weekly and viral cultures were obtained from the cervix and vulva. Decisions regarding mode of delivery were left to the discretion of the attending obstetrician.

Main Outcome Measures:

Delivery by caesarean section for recurrent genital herpes infection. Number of episodes of recurrent genital herpes infection and number of episodes of asymptomatic viral shedding during the treatment period. In addition blood was taken at two weekly intervals to determine acyclovir levels.

Results:

The total number of women recruited was 63 (31 received acyclovir and 32 received placebo). The number of women undergoing delivery by caesarean section for recurrent herpes at the time of delivery was 12 (19%). The odds ratio for delivery by caesarean section in women taking acyclovir, compared with those taking placebo, was 0.44 (95% CI 0.09-1.59). The odds ratio for clinical recurrences during treatment was 0.10 (95% confidence interval 0.00-0.86) and the odds ratio for clinical recurrence or asymptomatic shedding during treatment was 0.32 (95% CI 0.05-1.56).

Conclusion:

This trial was unable to demonstrate that acyclovir can significantly decrease the number of caesarean section deliveries; however, the number of clinical recurrences was significantly reduced. Two episodes of asymptomatic virus shedding both occurred in women taking acyclovir. At the present time there is little evidence to suggest that acyclovir should be used outside randomised controlled trials for the suppression of recurrent genital herpes infection during pregnancy.