The cryopreservation procedure provides couples the option of reducing the number of embryos initially replaced in the uterus and to freeze the unused embryos for future use.

Cryopreservation reduces the number of fertility drug stimulations and subsequent egg retrievals required. During an egg retrieval multiple eggs may be harvested and fertilized. A maximum number of embryos, usually four, are transferred often leaving additional embryos. With cryopreservation, these extra embryos can be saved for a future transfer, making additional costly retrievals unnecessary.

It is important to note that not all of the unused embryos will be frozen for later use. Only those that appear to be of sufficient quality to survive the cryopreservation procedure will be chosen. Because, typically, three or four embryos are transferred into the uterus, cryopreservation reduces the chance of having twins or triplets. Quadruplets are a rare occurrence.

Frozen embryos may be thawed and transferred to the woman¿s uterus during her natural cycle. Alternatively, complete hormonal replacement may be undertaken to create an entirely artificial cycle in which to replace the thawed embryo(s). The embryo(s) are placed in an environment in which growth and development are enhanced.