[Leflunomide: assessing teratogenic risk during the first trimester of pregnancy]

To assess the teratogenic risk associated with leflunomide during the first quarter of pregnancy, and to establish guidelines to minimize said risk.

Literature search using tertiary, secondary, and primary sources related to teratogenicity, including databases (MEDLINE and EMBASE) and specific webs. The information required for assessment, as well as for the establishment of criteria was collected.

Leflunomide demonstrated an increased risk of fetal death and teratogenic effects in animals. No major or minor malformation cases have been reported in humans regarding leflunomide, which is classified within category X of fetal risk. A wash-out regimen may possibly reduce the risk for fetal harm.

Conception scheduling or early pregnancy detection is required for better clinical counselling and the avoidance of unnecessary risk.