I did not see Eric's talk, but the teratogenicity of leflunomide is questioned in human case series. It is based upon animal models:

Here is one series https://pubmed.ncbi.nlm.nih.gov/29222350/

Here is the Mother To Baby pdf: https://mothertobaby.org/fact-sheets/leflunomide-pregnancy/

Nonetheless, if I had a patient on leflunomide who got pregnant, I would stop it and do a washout, but I am no longer as adamant with strict contraception on leflunomide as I was back in the days before these large case series became apparent.