In utero exposure to immunosuppressive drugs: experimental and clinical studies

Over the last few decades, the number of pregnant women under immunosuppressive (IS) therapy following transplantation or autoimmune diseases has increased. At first, IS drugs, including prednisone, azathioprine, and cyclosporine A were used, but now new molecules such as tacrolimus and mycophenolate mofetil have appeared. These IS drugs cross the placental barrier and enter into the fetal circulation, which poses a risk for fetal development. Experimental data have shown that IS drugs often have deleterious effects on fetuses, while human data have reported an increased rate of abortion, prematurity, intrauterine growth retardation (IUGR), and low birth weight, without significant increases in malformation rates. However, only limited information is available about the newly used molecules. Although fetal and neonatal data are reassuring, long-term effects of IS drugs on fertility, immune response and renal function, as well as the consequences of prematurity and IUGR, should be monitored.