Egg freezing (oocyte cryopreservation)

Why people freeze eggs

People freeze eggs for medical reasons — for example, before cancer treatment that may affect fertility — or to keep future options open. Understanding what egg freezing can and cannot promise is important before deciding.

How eggs are frozen

The HFEA describes the process: screening, around two to three weeks of ovarian stimulation as in an IVF cycle, egg collection under sedation, and then freezing. Freezing is now usually done by vitrification, an ultra-fast method that prevents the ice crystals that could otherwise damage the egg. To use the eggs later, they are thawed and injected with sperm (ICSI) to try to create embryos.

Why age matters

The HFEA is clear that the age at which eggs are frozen is the single biggest factor in later success, because egg quality declines with age — so eggs frozen earlier generally give a better chance of a future pregnancy. Because frozen-egg outcome data are based on relatively small numbers, the HFEA suggests comparing against age-banded IVF success rates using your own eggs. An ovarian reserve test can inform the conversation, but does not measure egg quality.

Storage rules and cost (UK)

Since 1 July 2022, UK law allows eggs (and sperm and embryos) to be stored for any period up to a maximum of 55 years from the date they are first stored. To keep storage lawful, you need to renew your consent every 10 years, so it is important to keep your contact details up to date with the clinic. Egg freezing also involves ongoing storage fees. Confirm current rules and total costs with your clinic before you start.

Rules differ between countries. If you are outside the UK, check the storage limits and consent requirements that apply where you live.