Freezing eggs for future use
- Published: Monday, 15 August 2016
The ability to store sperm, eggs and embryos is an important part of assisted conception, but until recently the science of egg cryopreservation was not well developed and not as successful as Cryopreserving sperm and embryos. However, recent developments have improved both the survival of eggs and the chance of achieving of pregnancy.
You may want to consider freezing your eggs if you want or need to delay childbearing in order to pursue educational, career or other personal goals, if you are a woman diagnosed with cancer or other medical reasons that could affect their fertility and if there's a family history of early menopause. Some forms of early menopause (premature ovarian failure) are genetically-linked. Egg freezing offers a chance to preserve eggs before they are all depleted.
When should you freeze your eggs?
The best time to pursue egg freezing, or oocyte cryopreservation, is in the prime reproductive years — a woman’s 20s and early 30s — in order to take advantage of premium egg quality and quantity. A woman is born with all of the eggs she will ever have, and over time they diminish in number and cellular integrity. This decline explains why a woman in her 40s has only a 5 percent chance for becoming pregnant each month, and her eggs have an increased chance for aneuploidy after age 45.
The best way to freeze eggs is to undergo a cycle of IVF treatment using medicines to stimulate a number of follicles to grow. When the follicles are at the correct size a final injection is given to allow the eggs to mature. The optimum time to cryopreserve eggs is at this mature stage (known as the metaphase stage).
Freezing of immature eggs may be appropriate in certain situations, but this may lead to a lower chance of achieving a pregnancy. These may be frozen and then matured in a laboratory later but this is currently considered experimental. There are two ways to cryopreserve eggs: slow cooling and vitrification. Slow cooling, freezing should take place within two hours of egg collection using specific cryoprotectants ( protective freezing solutions) and vitrification is an ultra fast way of freezing, eggs may survive better, but there are no studies about long-term safety and reliability.
When frozen eggs are thawed or warmed intracytoplasmic sperm injection (ICSI) seems to be the best method to fertilize them.
It is important if you are considering freezing eggs that we discuss the benefits and limitations of the procedure. Appropriate counseling should be offered and you should understand the chances of achieving a pregnancy.