How Long Can Frozen Eggs Be Stored?

Once oocytes have been vitrified, they do not deteriorate over time. They remain in exactly the same condition as at the moment they were vitrified, meaning they can remain frozen indefinitely.

Is there a maximum time limit for storing frozen eggs?

There is no strict time limit. It is reasonable to preserve them for as long as the woman wishes and as long as their use is medically appropriate. In other words, as long as the woman intending to use them is in good health and able to carry a pregnancy. Therefore, frozen eggs do not have an expiration date.

Why do eggs not deteriorate while frozen?

The technique currently used in the laboratory (vitrification) allows oocytes to be preserved at extremely low temperatures, stored in liquid nitrogen at -196ºC. This completely stops cellular activity.

Does the time spent frozen affect the chances of pregnancy?

No. The length of time the eggs remain frozen does not affect their chances of success. The most important factor is the woman’s age at the time the eggs were vitrified.

What does the quality of eggs depend on after thawing?

Again, the most important factor is the woman’s age at the moment of vitrification, since egg quality declines with age. As the age of the egg increases, survival rates after thawing tend to decrease.
The experience of the embryologist performing the vitrification procedure in the laboratory is also important.

What happens when a woman decides to use her frozen eggs?

Once the necessary prior medical evaluation has been carried out, the endometrium is prepared to receive an embryo. At the same time, the biologists proceed to warm (devitrify) the oocytes and perform the in vitro fertilization technique known as ICSI (Intracytoplasmic Sperm Injection). From that point, embryo culture begins and usually lasts 5–6 days, after which one embryo can be transferred to the uterus, while any remaining embryos may be vitrified.

Dr. Alicia Herencia, gynaecologist at IB Madrid and coordinator of the Instituto Bernabeu Specialised Unit in Oocytes Cryopreservation.