Time course of the regression of asymptomatic bacterial vaginosis in pregnancy with and without treatment

Am J Obstet Gynecol. 2004 Feb;190(2):363-70. doi: 10.1016/j.ajog.2003.08.020.


Objective: The purpose of this study was to determine the effectiveness of treatment over time for bacterial vaginosis in pregnancy and the probability of spontaneous resolution with placebo.

Study design: Women with asymptomatic bacterial vaginosis on Gram stain were assigned randomly at 16 to 23 weeks of gestation to receive two 2-g doses of metronidazole or placebo 48 hours apart and were re-evaluated for changes in Gram stain score on one occasion > or =2 weeks later.

Results: Of 658 women who underwent metronidazole therapy, treatment was successful (score, <7) in 78% of those women who were seen at 2 to 3.9 weeks of gestation, which was similar to women seen > or =10 weeks after treatment. In 683 women who underwent placebo therapy, spontaneous resolution increased significantly from 13% at 2 to 3.9 weeks of gestation to 36% at > or =10 weeks of gestation. Spontaneous resolution was more common with lower vaginal pH or lactobacilli on Gram stain at the time of random assignment.

Conclusion: The effectiveness of metronidazole therapy of bacterial vaginosis persists for > or =10 weeks. Women who underwent placebo therapy had significant remission of bacterial vaginosis over > or =10 weeks. Remission was more common when the initial vaginal microbiologic disturbances were less severe.

Publication types

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

MeSH terms

  • Adult
  • Anti-Infective Agents / therapeutic use*
  • Female
  • Humans
  • Metronidazole / therapeutic use*
  • Pregnancy
  • Pregnancy Complications, Infectious / drug therapy*
  • Remission, Spontaneous
  • Treatment Outcome
  • Vaginosis, Bacterial / drug therapy*


  • Anti-Infective Agents
  • Metronidazole