Many women are making the choice to freeze eggs to improve their chance to have children when they are ready. Egg freezing is a new technology, but already worldwide, more than 2000 healthy babies have been born from eggs that were frozen and later fertilized using IVF. Common questions asked by women are “how long can I keep my eggs frozen?” and “will my frozen eggs deteriorate over time”?
Egg freezing is relatively a very new option for women. Until recently, the challenge of freezing eggs had scientists stumped. Older methods of slow freezing commonly resulted in ice crystal formation which critically damaged many eggs. We have learned many lessons from the storage of frozen embryos, which has been around for much longer.
Vitrifiction has recently been discovered, and excitingly has been found to be especially good for storing eggs. “Vitrification” comes from the Latin word “vitrum” which means “glass”. In the lab, we put eggs into a specially designed vitrification fluid containing sugars and cryo-protection molecules. Eggs are then cooled with liquid nitrogen (to a temperature of -200 degrees celcius) – and this happens so quickly that no damaging ice crystals have the chance to form. Instead what happens is the eggs “solidify” into a glass like structure. They remain safely stored, stable and suspended in time, until the time comes to use them. In theory, eggs could remain like this for decades without experiencing any decline or decay.
Although there are not yet studies reporting pregnancy outcomes from eggs that have been frozen for more than 10 years, results from studies of frozen eggs used to date have been extremely positive.