Why consider egg freezing?

Fertility rates are very closely linked to age. As a woman ages the quality of the eggs produced becomes poorer. The quality of eggs is a major factor determining the chances of pregnancy. The decline is egg quality starts to become significant after the mid-thirties and declines more rapidly over the age of 40. Freezing your own eggs at a time in your life when the ovaries are able to produce eggs or when egg quality is better may give options for fertility in the future.

This method may therefore suitable for

1. Women who may have to undergo cancer treatment with the possibility of loss of function of the ovaries after this time (Click here for more info)
2. Women who have a family history of premature menopause
3. Women who have ethical or religious concerns regarding freezing of embryos
4. Women who wish to delay starting a family to a time when they feel best able to provide for a child emotionally and financially

The process

Eggs are the largest cells in the body and contain a lot of water. The freezing process may be performed by a quick cooling method known as vitrification or by a slow-rate freezing method. Once eggs are frozen they are stored at very low temperatures in liquid nitrogen. However the freezing process may cause ice crystals to form inside which when the egg is thawed causes it to burst. Methods of freezing and thawing are constantly being researched in the hope of improving survival rates which are currently approximately 55%.

As only a proportion of eggs may survive the freezing and thawing process and not all eggs may fertilise it is necessary to create more than one egg to give a chance of pregnancy in the future. This means undergoing a process similar to IVF treatment (Click here for more info). In addition as freezing eggs tends to harden the outer coating an additional process called ICSI (intracytoplasmic sperm injection) is used to help sperm penetrate the egg.

Currently the HFEA allows eggs to be stored in this way for a maximum of 10 years. In exceptional circumstances this may be extended.

Success rates and safety

Egg freezing is still experimental with only a handful of births using this method in the UK. Current success rates are estimated to be between 5-10%. However with further research in to the techniques of freezing and thawing eggs success rates are expected to improve in the future. Recent advances particularly from groups in Italy have improved pregnancy rates to around 25%. We recently held the UK’s first egg freezing symposium examining these new techniques. So far, little is known about the potential risks to a baby born from a frozen egg, as the total numbers of births in the world are still only in the hundreds. However from the births so far they are no immediate causes for concern. Follow-up of these and future births will be important to assess the long-term safety.