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MotherToBaby

Medications and More during pregnancy and breastfeeding

Metronidazole (Flagyl®)

Selected References:

  • Ajiji P, et al. 2021. Investigating the efficacy and safety of metronidazole during pregnancy; A systematic review and meta-analysis. Eur J Obstet Gynecol Repr Biol; X,11,100128. 
  • Boissiere-O’Neill T, et al. 2026. Exposure to Systemic Antimicrobials During Pregnancy and Risk of Miscarriage: A Population-Based Registry Study. BJOG; 133(7):1394-1404.  
  • Burtin P, et al. 1995. Safety of metronidazole in pregnancy: a meta-analysis. Am J Obstet Gynecol; 172(21):525-529.  
  • Cantu JM, Garcia-Cruz D. 1982. Midline facial defect as a teratogenic effect of metronidazole. Birth Defects Orig Artic Ser; 18(3 Pt A):85-88.  
  • Caro-Paton T, et al. 1997. Is metronidazole teratogenic? A meta-analysis. Br J Clin Pharmacol; 44:(2)179-182.  
  • Cram LF, et al. 2015. Genitourinary infections and their association with preterm labor. Am Fam Physician; 65(2), 241–248. 
  • Czeizel AE, Rockenbauer M. 1998. A population-based case-control teratologic study of oral metronidazole. Br J Obstet Gynaecol; 105(3):322-327.  
  • Diav-Citrin O, et al. 2001. Pregnancy outcome after gestational exposure to metronidazole: a prospective controlled cohort study. Teratology; 63(5):186-192.  
  • Einarson A, et al. 2000. Can we use metronidazole during pregnancy and breastfeeding? Putting an end to the controversy. Can Fam Physician; 46:1053-1054. 
  • Finegold SM. 1980. Metronidazole. Ann Intern Med; 93:585-587. 
  • Flagyl® Prescribing Information. Available online at: https://www.accessdata.fda.gov/drugsatfda_docs/label/2024/020334s015lbl.pdf. Accessed June 2025. 
  • Gilbert NM, et al. 2013. Urinary tract infection as a preventable cause of pregnancy complications: Opportunities, challenges, and a global call to action. Glob Adv Health Med; 2(5):59–69.  
  • Gray MS, et al. 1961. Further observations on metronidazole (Flagyl). Br J Vener Dis; 37:278-279.  
  • Heisterberg L, Branebjerg PE. 1983. Blood and milk concentrations of metronidazole in mothers and infants. J Perinat Med; 11:114-120.  
  • Kazy Z, et al. 2005. Teratogenic potential of vaginal metronidazole treatment during pregnancy. Eur J Obstet Gynecol Reprod Biol; 123(2):174-178.  
  • Koss CA, et al. 2012. Investigation of Metronidazole Use during Pregnancy and Adverse Birth Outcomes. Antimicrob Agents Chemother; 56(9): 4800-4805.  
  • Löfmark S, et al. 2010. Metronidazole is still the drug of choice for treatment of anaerobic infections. Clin Infect Dis; 50(S1):S16–S23.  
  • Muanda FT, et al. 2017. Use of antibiotics during pregnancy and risk of spontaneous abortion. CMAJ; 189(17):E625-E633. 
  • Nwosu OC, Bloom K. The safety of metronidazole in pregnancy. Health Care Women Int; 2021;42(4-6):726-738.  
  • Omranipoor A et al. 2020. Association of antibiotics therapy during pregnancy with spontaneous miscarriage: a systematic review and meta-analysis. Arch Gynecol Obstet; 302(1): 5-22. 
  • Passmore CM, et al. 1988. Metronidazole excretion in human breastmilk and its effect on suckling neonates. Br J Clin Pharmacol; 26(1):45-51.  
  • Piper JM, et al. 1993. Prenatal use of metronidazole and birth defects: no association. Obstet Gynecol; 82(3):348-352.  
  • Rosa FW, et al. 1987. Pregnancy outcomes after first trimester vaginitis drug therapy. Obstet Gynecol; 69(5):751-755.  
  • Sheehy O, et al. 2015. The use of metronidazole during pregnancy: a review of evidence. Curr Drug Saf; 10(2):170-179. 
  • Workowski KA, Bolan GA. 2015. Sexually transmitted diseases treatment guidelines, 2015. MMWR Recomm Rep; 64:1-137. 

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