Cryopreservation
Generally not more than three embryos are transferred to the uterus or tubes in infertility treatment in order to avoid multifetal pregnancy. It is possible to freeze the excess embryos for future using. The advantage of freezing embryos is that they can be transferred in a future cycle without the woman having to undergo the same treatment and surgery. The embryos can be frozen for up to five years, although this can be extended to ten years in exceptional circumstances.