Fertility preservation options for women include oocyte cryopreservation, commonly known as egg freezing. It is the process in which multiple eggs are grown from within the ovaries over a two week period. Egg freezing culminates with an outpatient procedure where the eggs are removed and brought to the lab to undergo vitrification or the “freezing” process. The eggs remain frozen in the lab until the patient is ready to use them. Many women wonder if they choose to freeze their eggs — how long will they last?
First, The Science of Storing Eggs
Cryopreservation is the process of freezing tissue in an effort to preserve them for future use. In current practice, the method of freezing eggs is referred to as “vitrification” in which tissue is frozen in liquid nitrogen at roughly −196 °C/-321°F, allowing them to stay viable for future use when needed in the future. During the time the tissue is frozen, no cell growth is occurring. Once thawed, further cellular development of the egg can occur.
Other Factors to Consider
While technically speaking the eggs can remain frozen for as long as women desire, there are other factors women should keep in mind. The goal of fertility preservation is to have eggs frozen from a time when you were younger than from the time at which you plan to be ready to conceive. Eggs from a younger person are more likely to be chromosomally normal and lead to a live birth.
The chromosomal makeup of the egg plays a pivotal role in the likelihood of the egg contributing to a healthy embryo. After the egg has divided and (hopefully has the appropriate number of chromosomes), there are still several steps along the way to a live birth that may/may not occur successfully.
First, the egg must survive the thawing process. Next, it needs to be fertilized by sperm. If successfully fertilized, this newly formed embryo must continue to grow and divide to become a more developed embryo (called a blastocyst). Finally, this blastocyst must be placed within a uterus to implant and lead to delivery of a baby. Since having an appropriate number of chromosomes within the embryo is the greatest prognostic factor in predicting a successful implantation, freezing eggs at a younger age ultimately optimizes outcomes. Even at a younger age (and even in cases where multiple eggs are frozen at a young age), there still is a possibility that when you return to use the eggs and create embryos with them it does not lead to a successful pregnancy.
If the frozen eggs do not work, many women may try to conceive at the age that they are when they are coming back to use these frozen eggs. Depending on how old a woman is at the time (and other health factors), the prognosis for having a baby naturally may be lower, particularly after 40 years old.
While not everyone may desire to use their frozen eggs in the future, considerations for alternative family building options in the event the frozen eggs don’t result in a successful outcome is important. This includes contemplating if using a donor egg or embryo or if exploring adopting are possible options for you. For patients who are not open to alternative options, delaying use of their frozen eggs may lower their chances of a live birth from their own eggs.
There is no time limit for how long an egg can be cryopreserved, but there are other considerations that should be taken into account if you are deciding to freeze your eggs. While deciding to use your frozen eggs may be intricate decision, understanding the entire process and its stages is an essential first step to take in making your choice.
Nidhee Sachdev, MD FACOG, is a reproductive endocrinology and fertility expert that practices at OC Fertility in Newport Beach, California. Dr. Sachdev spent the early part of her education at UC San Diego for undergrad followed by medical school at UC Irvine. She then went on to complete OBGYN training at the University of Chicago Medicine followed by REI Fellowship at the NYU Langone Fertility Center.
Learn more about OC Fertility’s egg freezing practice on Freeze.
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