A double-blind, randomized, placebo-controlled trial of acyclovir in late pregnancy for the reduction of herpes simplex virus shedding and cesarean delivery

Am J Obstet Gynecol. 2003 Mar;188(3):836-43. doi: 10.1067/mob.2003.185.


Objective: The purpose of this study was to assess the efficacy of acyclovir in the reduction of herpes simplex virus culture and polymerase chain reaction positivity and cesarean delivery.

Study design: Women with recurrent genital herpes simplex virus were randomized to acyclovir 400 mg three times daily or placebo from 36 weeks of gestation until delivery. A subset of daily specimens for herpes simplex virus culture and DNA polymerase chain reaction was self-collected. Analyses used chi(2), Fisher exact, and Mann-Whitney U tests.

Results: Lesions occurred at delivery among 11 of 78 women (14%) who received placebo and 4 of 84 women (5%) who received acyclovir (P =.08). Herpes simplex virus culture and polymerase chain reaction positivity near delivery occurred in 7% and 34% women in the placebo group and 0 and 2% in the acyclovir group (P =.03 and <.01, respectively). Cesarean delivery for herpes simplex virus occurred in 8 of the women (10%) in the placebo group and in 3 of the women (4%) in the acyclovir group (P =.17). Despite reductions in herpes simplex virus detection, 6% of the women who received acyclovir had herpes simplex virus detected by polymerase chain reaction on >20% of days. Neonatal outcomes were similar between groups.

Conclusion: Acyclovir significantly reduced, but did not eliminate, herpes simplex virus lesions and detection in late pregnancy.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acyclovir / therapeutic use*
  • Adult
  • Antiviral Agents / therapeutic use*
  • Cesarean Section*
  • Double-Blind Method
  • Female
  • Follow-Up Studies
  • Herpes Genitalis / pathology
  • Herpes Genitalis / virology*
  • Humans
  • Placebos
  • Pregnancy
  • Pregnancy Complications, Infectious / drug therapy*
  • Pregnancy Complications, Infectious / pathology
  • Pregnancy Outcome
  • Pregnancy Trimester, Third
  • Simplexvirus / isolation & purification
  • Simplexvirus / physiology*
  • Virus Shedding*


  • Antiviral Agents
  • Placebos
  • Acyclovir