Effect of oral N-acetyl cysteine on recurrent preterm labor following treatment for bacterial vaginosis

Int J Gynaecol Obstet. 2009 Jan;104(1):44-8. doi: 10.1016/j.ijgo.2008.08.026. Epub 2008 Oct 11.


Objective: To evaluate the effect of N-acetyl cysteine (NAC) on gestational age at delivery in women with previous preterm labor and bacterial vaginosis.

Methods: A randomized, double-blind, placebo-controlled trial with 280 women between 16 and 18 weeks of pregnancy who had 1 previous preterm birth and had just been successfully treated for bacterial vaginosis with metronidazole for 1 week. The women were randomized to receive 0.6 g of NAC per day plus 17-hydroxyprogesterone caproate (17-OHPC) or placebo plus 17-OHPC until 36 completed weeks of pregnancy or active labor. A vaginal swab was taken during labor.

Results: Reaching 36 weeks of pregnancy was more frequent (P<0.05) and gestational age at delivery was significantly higher in the NAC than in the placebo group (37.4 weeks+/-0.4 weeks vs 34.1 weeks+/-1.2 weeks, P<0.05). The discontinuation rate was 11.4% in the NAC group.

Conclusions: Oral NAC was found to reduce the recurrence of preterm birth in patients with bacterial vaginosis.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Acetylcysteine / administration & dosage*
  • Administration, Oral
  • Adult
  • Anti-Infective Agents / therapeutic use
  • Drug Therapy, Combination
  • Female
  • Free Radical Scavengers / administration & dosage*
  • Humans
  • Metronidazole / therapeutic use
  • Obstetric Labor, Premature / prevention & control*
  • Pregnancy
  • Pregnancy Complications, Infectious / drug therapy*
  • Pregnancy Complications, Infectious / microbiology
  • Vaginosis, Bacterial / drug therapy*
  • Young Adult


  • Anti-Infective Agents
  • Free Radical Scavengers
  • Metronidazole
  • Acetylcysteine