For how long can cryopreserved embryos be used?

Quite a number of media organizations a few weeks ago reported on what, likely, represented the “oldest” frozen embryo ever to lead to pregnancy. The embryo had been cryopreserved for 24 years before being, finally, transferred.

As an interesting side note, the woman who had this embryo transferred was, herself, only two years older than the embryo she received through an anonymous donation. The previously reported “oldest” embryo had spent 19 years and 7 months in cryopreservation before thaw.

All of this should not surprise. Indeed, we can expect this record to be broken soon because, once an embryo (and this also applies to eggs and semen) is properly cryopreserved, it no longer ages. Theoretically, these embryos can be preserved for 100 (or more years). Think about it: future generations then can thaw out our embryos. This would be the earliest form of real time travel for humans!

When this news broke, Vitaly A. Kushnir, MD, Director of Fertility Preservation and CME at CHR, was called upon to contribute an explanation. In an article by Olivia Campbell published on Tonic, Dr. Kushnir explained the two principal techniques used in freezing eggs and embryos:

“The passage of time likely does not matter as long as the conditions in the storage tank are maintained. The technique of freezing and thawing is more important. Slow freezing uses an automated system to lower the temperature gradually as cryoprotectants are added; vitrification is a manual process but because it’s very fast, it helps avoid the formation of damaging ice crystals.”

This is a part of the February 2018 CHR VOICE.