Since the first report of a successful pregnancy following the transfer of a cryopreserved human embryo , cryopreservation has become wide spread practice in most IVF laboratories. Simply stated, cryopreservation maximizes IVF cycle yield without the fear of embryo wastage. Cryopreservation decreases the risk of multiple implantation by allowing the transfer of fewer embryos, reduces the risk of ovarian hyperstimulation by allowing transfer in nonstimulated cycles, and permits delay in embryo replacement in cases of suboptimal or adverse maternal conditions.  
 
It appears that despite the inevitable loss of some embryos in the freeze-thaw process, high quality embryos after thawing have as much chance for implantation as similar quality fresh embryos and should be regarded equivalent to their fresh counterparts in decisions regarding the number of embryos to be transferred.