Vitrification is a “flash freezing” process that requires cryoprotectants, think of antifreeze, that dehydrate, and replace the water in your embryo to prevent ice crystal formation, which could harm your embryo during the warming process. Embryos can remain in this glass-like state indefinitely.

Embryo warming is a procedure that takes place on the day of your transfer. Embryos are usually warmed and rehydrated about 2 hours before your appointment in preparation for the transfer.