Egg freezing (oocyte freezing)

What egg freezing involves

The UK fertility regulator, the HFEA, says egg freezing “involves collecting a woman's eggs, freezing them and then thawing them later on so they can be used in fertility treatment.”

The collection follows IVF: “You'll then start the IVF process, which usually takes around two to three weeks to complete.” Then, “instead of mixing the eggs with sperm (as in conventional IVF) a cryoprotectant (freezing solution) will be added to protect the eggs. The eggs will then be frozen either by cooling them slowly or by vitrification (fast freezing) and stored in tanks of liquid nitrogen.”

Using them later requires ICSI: “Eggs that have been frozen and thawed must be fertilised using a fertility treatment called ICSI , as the freezing process makes the outer coating around the eggs tougher and sperm may be unable to penetrate it naturally under IVF.” See ICSI.

When it is used

The HFEA starts from age: “A woman's chances of conceiving naturally fall as she gets older because the quality and number of her eggs drops.” It lists reasons including:

• “You have a medical condition or need treatment for a medical condition that will affect your fertility, such as cancer”
• “You're worried about your fertility declining but you're not ready to have a child or you haven't found the right partner – this is often called 'elective egg freezing'.”

Whether it is appropriate in a particular case is a clinical decision for the treating doctor. This directory does not make that judgement. Freezing embryos instead of eggs is covered on the embryo freezing page.

What the regulator says about risks

The HFEA states: “IVF is mostly very safe, although some women do experience side effects from their fertility drugs. These are usually mild, but in extreme cases women can develop ovarian hyperstimulation syndrome (OHSS), which is potentially fatal, so you should familiarise yourself with the symptoms.”

And, bluntly: “The major risk is that it won't work”. It adds: “It's also important to know that as you get older, there is more risk of pregnancy-related complications and health problems to both you and your baby.” It calls egg freezing “a rapidly changing field.”

Questions

Is egg freezing the same as oocyte freezing?

Yes. This page covers both names; the directory has merged its two listings for them into this one.

Can frozen eggs be used with ordinary IVF?

The HFEA says thawed eggs “must be fertilised using a fertility treatment called ICSI”.

What is the main risk?

The HFEA says “The major risk is that it won't work”. Its statement on the risks of the drugs is quoted in full above.

Sources

• HFEA, Egg freezing, read 25 September 2026.
• The Assisted Reproductive Technology (Regulation) Rules, 2022, G.S.R. 419(E), 7 June 2022, para 10.1 (not changed by the Amendment Rules, 2026, G.S.R. 491(E)), read 25 September 2026.
• Clinic data: each clinic's own website, as read by this directory; registry level from the National ART & Surrogacy Registry extract.