Ondansetron use during pregnancy does not appear to increase congenital malformations risk

  • Kaplan YC & al.
  • Reprod Toxicol
  • 5 Mar 2019

  • curated by Sarfaroj Khan
  • UK Clinical Digest
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  • This meta-analysis suggests that ondansetron use during pregnancy is not associated with an increased rate of overall major congenital malformations, heart defects, orofacial clefts, genitourinary malformations and hypospadias.

Why this matters

  • Current nausea and vomiting of pregnancy treatment guidelines suggest that ondansetron may be considered if first-line drugs fail to suppress maternal symptoms.
  • Studies investigating the safety of maternal ondansetron use have reported inconsistent findings.

Study design

  • Six studies involving 3914 ondansetron-exposed infants and 1,563,139 healthy control individuals met eligibility criteria after a search across electronic databases.
  • Primary outcome: risk for overall major congenital malformations.
  • Secondary outcome: risk for heart defects, orofacial clefts, isolated cleft palate, genitourinary malformations and hypospadias.
  • Funding: None.

Key results

  • Ondansetron use during pregnancy was not associated with a significantly increased risk for overall major congenital malformations vs control group (OR, 1.16; 95% CI, 0.92-1.45).
  • Compared with the control group, ondansetron group did not show significant increased risk for:
    • heart defects (OR, 1.26; 95% CI, 0.90-1.77);
    • orofacial clefts (OR, 0.89; 95% CI, 0.32-2.50);
    • isolated cleft palate (OR, 1.13; 95% CI, 0.43-2.97);
    • genitourinary malformations (OR, 1.55; 95% CI, 0.89-2.69);
    • hypospadias (OR, 1.61; 95% CI, 0.69-3.75).


  • Majority of the studies did not report data on exposure time windows, dose and duration.
  • Characteristics of the control groups widely differed between studies.