Prenatal exposure to mycophenolate mofetil: an updated estimate.

Mycophenolate mofetil (MMF) has become a major therapeutic option in the management of patients undergoing transplantation, as well as in the treatment of autoimmune conditions. Case reports have suggested that MMF use during pregnancy is associated with a specific pattern of congenital malformations. Because many pregnancies are unplanned, it is imperative to assess the teratogenic risk of MMF. Using the Organization of Teratology Information Specialists network, we prospectively identified and followed pregnant women exposed to MMF during pregnancy to update this teratogenic potential. Ten cases were identified and all received the drug during embryogenesis at the recommended doses (500 to 1500 mg daily). There were four miscarriages and one elective abortion due to fear of teratogenesis. None of the five live births had malformations. It is possible that, similar to other human teratogens discovered first by case reports, the absolute risk from MMF may be smaller than originally calculated based on case reports. Because the major malformations phenotypic of MMF may be visualized in utero (e.g., microtia, cleft palate, congenital diaphragmatic hernia, and cardiac malformation), diagnostic imaging should be performed.