Some couples are fortunate enough to collect large number of embryos from one egg collection. So, additional viable embryos may be frozen
Cryopreservation for future use
Cryopreservation allows the patient to limit the number of embryos transferred without discarding the unused embryos that could be used for a future pregnancy. The embryos may be kept in storage for several years. By transferring frozen-thawed embryos into the uterus, some patients have achieved more pregnancies in different years from just one egg collection.