Nephsap review: Transplantation

A question encountered on our recent Nephsap review on transplantation:
What regimen would be the safest in pregnancy? If one had to choose between CNI + prednisone or CNI+ azathioprine. The groups were divided.
What is the data?
As you go down the list in immunosuppresive medications: most are C and below and no medication is a Risk category A or B.  Cyclosporine has the most data with tacrolimus with extrapolated data. Aza and MMF would be close to category D compared to CNIs which are more of a category C. Steroids would also fall in category C.  From a clinical prespective, the safest immunosuppression for a woman who wishes to get pregnant seems to be a combination of controlled CNI and prednisione. MMF should be discontinued.
What if you were on a steroid sparing protocol? Would you add steroids or AZA instead of MMF?
Azathioprine is teratogenic in animal studies.  It does cross the placenta/ and hematologic toxicities can happen to the fetus.  But a lot of pregnancies have been documented successfully at many transplant centers with AZA.  So some centers would choose to add AZA in this case but some might just do steroids and CNI. Due to lack of data, there is really no right answer. Risks and benefits of all agents have to be discussed and decisions made on an individual basis.

Ref:
http://www.ncbi.nlm.nih.gov/pubmed/21266268
http://www.ncbi.nlm.nih.gov/pubmed/20685549
http://www.ncbi.nlm.nih.gov/pubmed/18368705
http://www.ncbi.nlm.nih.gov/pubmed/16095516