But scientists have been recently warning women that they could not expect to wait to have children in their late 30s and early 40s because they might fail to conceive.

Speaking at a press briefing at the Royal Institution in London, Dr Simon Fishel said: "There are lots of women of reproductive age who are going to want to have a career and they are not going to be frightened off by being told they should have children in their 20s."

But Peter Braude, director of the centre for pre-implantation genetic diagnosis at Guy's Hospital, London, warned that experts could not yet be sure the embryo-freezing process was safe and he said it was known that several cells were lost during the process although it doesn't seem to harm anything.

Women can currently pay to have their eggs frozen for non-medical reasons, but safety concerns mean many clinics will only carry out this practice for cancer patients whose fertility maybe destroyed by chemotherapy.

The high water content of eggs means that when it is frozen ice crystals that form  can cause serious damage and destroy the egg but fertility experts say a new process, called "vitrification", where the water is drawn out and chemicals added is proving increasingly successful.