Send to

Choose Destination
Ann Rheum Dis. 2018 Apr;77(4):500-509. doi: 10.1136/annrheumdis-2017-212078. Epub 2017 Dec 8.

Leflunomide use during pregnancy and the risk of adverse pregnancy outcomes.

Author information

Research Center, CHU Sainte-Justine, Montreal, Quebec, Canada.
Faculty of Pharmacy, University of Montreal, Montreal, Quebec, Canada.
Global Pharmacovigilance and Epidemiology, Sanofi Genzyme, Cambridge, Massachusetts, USA.
Global Pharmacovigilance and Epidemiology, Sanofi, Bridgewater, New Jersey, USA.



Leflunomide is known to be embryotoxic and teratogenic in rodents. However, there is less evidence in humans. We quantified the risk of major congenital malformation (MCM), prematurity, low birth weight (LBW) and spontaneous abortion associated with leflunomide exposure during pregnancy in humans.


From a cohort of 289 688 pregnancies in Montreal, Quebec, Canada, from 1998 to 2015, first-trimester leflunomide exposure and other antirheumatic drug exposures were studied for their association with MCM and spontaneous abortions. Also second or third-trimester leflunomide exposures were examined for associations with prematurity and LBW. Logistic regression model-based generalised estimating equations were used.


51 pregnancies were exposed to leflunomide during the first trimester, and 21 during the second/third trimesters. Adjusting for potential confounders, use of leflunomide during the first trimester of pregnancy was not associated with the risk of MCM (adjusted OR (aOR) 0.97, 95% CI 0.81 to 1.16; 5 exposed cases). No association was found between second/third-trimester exposure to leflunomide and the risk of prematurity (aOR 4.03, 95% CI 0.91 to 17.85; 7 exposed cases) nor LBW (aOR 1.06, 95%CI 0.90 to 1.25; 8 exposed cases). Pregnancy exposure to leflunomide was also not associated with the risk of spontaneous abortion (aOR 1.09, 95% CI 0.90 to 1.32; 11 exposed cases).


Maternal exposure to leflunomide during pregnancy was not associated with statistically significant increased risk of MCMs, prematurity, LBW or spontaneous abortions. However, given that relatively few women were exposed to leflunomide during pregnancy in this cohort, caution remains warranted.


Leflunomide; low birth weight; major congenital malformation; pregnancy exposure; spontaneous abortion

Conflict of interest statement

Competing interests: AB and JPZ declare no financial interest relating to the subject discussed in the manuscript; IS and SC are employees of Sanofi.

Supplemental Content

Full text links

Icon for HighWire
Loading ...
Support Center