What Is Embryo Freezing?
Embryos created in an IVF cycle are cryopreserved (frozen) on days 5-6 of development, called the blastocyst stage. If using PGT-A, embryos are frozen after they have been biopsied for PGT-A (genetic testing of the embryo). Many patients have more than one good quality embryo. One of these embryos will be selected to transfer in a later cycle while the remaining stay cryopreserved in liquid nitrogen.
These embryos can be cryopreserved by freezing them in liquid nitrogen. Through a series of carefully orchestrated steps called vitrification, the embryos are ultimately frozen at a temperature of –196 C, leaving them in a state of suspended animation in which they can remain for many years.
Success Rate Of Frozen Embryos
The pregnancy rates associated with replacing frozen embryos depend on the age of the patient and the quality of the embryos at the time of cryopreservation.
Top-quality embryos from young patients may yield pregnancy rates in excess of 50%. Poor-quality embryos may not even survive the thawing process. Most patients choose to do PGT-A to ensure they are transferring a chromosomally normal embryo.