A Baby Was Recently Born From a Frozen 27 Year Old Egg, Here’s How That Can Happen
The birth of a baby girl named Molly recently made headlines. The fact she was conceived following the freezing and thawing of an embryo was nothing new. Embryo freezing, also referred to as cryopreservation, has been around for decades and is now done regularly in fertility clinics around the world. What was unusual about Molly’s case was the timing; the embryo that ultimately led to her birth was created and frozen in 1992, a full 27 years earlier. The story of Molly, while record setting in terms of duration of embryo freezing, does not come as a surprise to fertility specialists. We have long known that when we freeze sperm or embryos in liquid nitrogen, at -320 degrees Fahrenheit, cellular metabolism is stopped in its tracks and there really shouldn’t be a theoretical upper limit as to the duration at which the specimen can stay frozen.
While embryo cryopreservation has been available clinically for a very long time, freezing eggs is relatively new. The first birth of a baby from frozen eggs dates back to 1986. However, slow freezing techniques to freeze eggs back then were so inefficient with extremely low success rates that clinics could not offer egg freezing to the public. That changed with refinements in techniques for egg cryopreservation and especially with the advent of “vitrification”, where eggs (and other cells and tissues) can be frozen quickly with high amounts of substances to protect the cell called cryoprotectants. This enables the cells to go from a liquid to a glass-like state and avoid the damage that can ensue from damaging ice crystal formation. While embryos had good success rates from slow freeze-thaw protocols, unlike eggs which are more fragile, vitrification has now also further improved embryo freezing success rates and is now standard of care for both eggs and embryos.
The birth of Molly after a 27 year freeze-thaw has raised the question of how long eggs can be successfully frozen. This is particularly important since eggs tend to be frozen on average far longer than embryos, since women often freeze eggs to protect against the age-related decline in fertility often many years before they are ready to start a family. While you cannot completely extrapolate the success with embryo freezing to egg freezing, the recent reports in the press do highlight the power of gamete and embryo cryopreservation. Eggs also should do well after long durations in a frozen state and probably even after a really long period of time in a liquid nitrogen bath. This should offer some additional measure of comfort to women who plan to freeze eggs, often without knowing when they may come back to use these eggs even if it is many years down the road.