Only 24 women over 50 gave birth via IVF in 2002. At present, the best chance this group has of conceiving is to use eggs donated by younger women. But donated eggs are in short supply and produce children with no genetic link to the birth mother, limiting the procedure’s appeal.

That situation is likely to change as egg-freezing techniques become more advanced, allowing women to store “young” eggs of high quality during their 20s or 30s, which can be defrosted for use later.

Although it has long been possible to freeze sperm, egg-freezing is more complicated because of the cell’s larger size and high water content. The first baby conceived using a frozen egg was born in 1986, but only about 300 more have been born worldwide since.

New techniques are changing this. A method called vitrification, developed in Japan, Denmark and the US, allows eggs to survive the thawing process much more reliably, and pregnancy rates using frozen eggs now approach those achieved with standard IVF.

It has been legal in Britain to fertilise thawed eggs since 2000. Two babies have already been born, and 22 clinics are licensed to offer the service.

Most women who freeze their eggs do so either because they have cancer and their treatment will leave them infertile, or because they have ethical objections to freezing embryos. But some women have already done undergone treatment for social reasons.

Last month Gillian Lockwood, of Midland Fertility Services, said that childless women in their 30s should think about freezing their eggs, as this would give them a better chance of having a baby a decade from now than relying on natural conception.

Many of these women may wait until they are in their 50s to thaw their eggs, and many doctors will find it harder to refuse them treatment if they are using their own eggs.

“Right now we are dealing with egg donation, but as egg-freezing becomes more mature this is going to become more of an issue,” Anne Steiner, of the University of North Carolina, said.

“If you have frozen your own eggs and are now 50-plus and want to use them, you are going to think you have a right to use them. They’re yours, why shouldn’t you fertilise them and get them back? We need to start the research to get a good idea of how parenthood at this age affects parents and children — physically and psychologically — if we are to decide what might be reasonable and what might not.”

Richard Paulson, who worked with Dr Steiner, said: “Egg-freezing will completely change the way we view assisted reproduction. It will become more than a therapy for infertility, but also a way of preserving fertility. I can’t imagine a 30-year-old would freeze her eggs intending to become a mother at 50, but sometimes life does not pan out the way you plan it.”

Another development is ovary tissue banking. Two cancer patients have given birth after having ovary tissue removed, frozen and replaced. There is no reason why the technique could not also be used by healthy women. It could have the further advantage of restoring a normal hormonal balance after the menopause, which could improve the chances of a healthy pregnancy.

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