Cryopreservation is used in infertility programs mainly to freeze and store sperm or to freeze "leftover" embryos from an IVF cycle.
As IVF programme involves the superovulation, Their chances of getting many oocytes and often many embryo. Since the risk of multiple pregnancies increases with the number of embryo transfers.
Many patients are left with spare or supernumerary embryos. These embryos are now possible to freeze & store them in Liquid nitrogen .so that patient can have another embryo transfer cycle without having to go through Superovulation and egg harvest.