Egg Freezing

What is egg freezing?

For many years it has been possible for couples undergoing IVF treatment to have embryos frozen and stored for future use. It has taken longer to develop methods for freezing eggs, as they are more vulnerable to the damage that can take place when cells are cooled. Techniques have now been developed that enable eggs to survive freezing and thawing, to be fertilized, develop into embryos, and form normal pregnancies. Eggs are treated using very specialised solutions, and are cooled very slowly, under computer control. They are then transferred to storage tanks containing liquid nitrogen.

Who needs egg freezing?

Egg freezing may be used in any situation where eggs are collected from a woman’s ovaries and there are no sperm available to fertilise them and create embryos. Women who have cancer may require treatment that will harm their ovaries and restrict their future fertility. If they do not have partner, and are therefore unable to store embryos, it is possible to freeze eggs so that their future fertility may be preserved (if only in a limited way). As it is necessary to use drugs to stimulate the ovaries in order that enough eggs develop for freezing to be carried out, women with certain types of cancer will not be able to undergo freezing, either because they need to start treatment immediately, or because their disease is sensitive to the drugs that are used in ovarian stimulation (e.g. oestrogen sensitive tumours).

Women who are suffering from a condition that may lead to premature ovarian failure, and, as a result, infertility, may also consider egg freezing.

Egg freezing is also available to women who are unable to start a family at present, but who are concerned about their future fertility.

Finally, egg freezing may be used as an emergency procedure for couples undergoing IVF, if for any reason, the male partner is unable to provide sperm at the time of treatment.

What does egg freezing involve?

In order to collect enough eggs to freeze, women must undergo drug treatment to stimulate their ovaries, in the same way as women undergoing IVF treatment. This takes two to five weeks.

The eggs are then collected under general anaesthetic as they would be normally for IVF or ICSI. Only eggs that are mature, i.e. are ready to be fertilized, can be frozen, and the embryologist will check the maturity of each egg prior to freezing.

When the eggs are required for treatment, they are thawed and fertilised using the ICSI technique as described above, in order to give the maximum chance of fertilisation.

How successful is egg freezing?

Egg freezing is a new technique and it takes time to accumulate results, as eggs may be stored for several years before they are used. Over a hundred babies have now been born worldwide, with no reports of any abnormality, but this is a very small number, and we cannot yet draw any definite conclusions about the safety of the technique.

What are the risks of oocyte freezing?

Early experiments on egg freezing suggested that cooling eggs resulted in damage to the arrangement of chromosomes, which prevented fertilization and normal development. Current techniques appear to have overcome this problem, and there have been no reports of abnormalities in babies born from frozen-thawed eggs. However, the numbers are still low, so we cannot yet draw any definite conclusions. Nevertheless, the data so far does not suggest any cause for concern.

How long can eggs be stored?

You may store your eggs for 10 years, but under certain circumstances this can be extended until you reach the age of 55.