Women who want to postpone motherhood to establish a career or find the right partner have been given new hope by research that shows the safety of an advanced egg-freezing technique.

The most exhaustive study yet of children born after the freezing procedure found that they appeared to be as healthy as those conceived normally or by IVF, paving the way for its widespread use.

The results are likely to embolden thousands of women in their twenties and thirties who are considering whether to place eggs on ice to improve their chances of starting a family when they are older.

Specialists said that the research, into a method known as vitrification, promises to lift the main barrier to routine egg freezing. While dozens of British women have already done this to preserve their fertility, medical groups had advised against it outside clinical trials because of limited evidence of its safety.

The study, led by Ri-Cheng Chian, of McGill University, in Montreal, Canada, assessed the outcomes of 200 children born from vitrified eggs. It found that the rate of birth defects was 2.5 per cent, which is comparable to natural pregnancies and IVF.

Dr Chian told The Times: “I have two daughters. If they wanted to preserve their fertility because they were 35 and not married, I would say, yes, they should use this technique. Even if they were 20 or 25 and wanted to use it for social reasons, I would recommend going ahead. We cannot yet say it is 100 per cent safe, but we are starting to amass good evidence that it is not risky so far as we can tell.

“The American Society for Reproductive Medicine says egg freezing for social reasons should happen only in clinical trials, because there isn’t enough information yet, but I think that is soon going to have to change.”

Gillian Lockwood, medical director of Midland Fertility Services, which offers egg freezing in Britain, said: “This is the sort of evidence we have all been seeking. I think in time it will come to be seen as positively perverse to refuse to allow women to have the chance to establish pregnancies with their own frozen eggs.”

She said that frozen eggs stored when women were in their twenties or thirties might eventually be shown to reduce the rate of birth abnormalities beyond that seen in the McGill study, which is published in the journal Reproductive Biomedicine Online. Such defects become more of a risk when older women conceive with their own fresh eggs.

Allan Pacey, secretary of the British Fertility Society, said that the society did not have a firm policy on egg freezing for social reasons. “A single study isn’t enough, but if more data like this emerges we would be more relaxed about it,” he said.

While it has long been possible to freeze sperm and embryos for use in fertility treatment years later, it has taken much longer to achieve this routinely for eggs. The prospects of wider use have recently been enhanced by the development of vitrification, which involves flash-freezing eggs after special preparation.

Up to 95 per cent of vitrified eggs survive the thawing process, compared with 50 to 60 per cent of those preserved by older slow-freezing techniques. Pregnancy rates for vitrification can be as good as for IVF with fresh eggs.

These advances may encourage more women to freeze eggs as a way of preserving their fertility, which starts to decline steeply when from the mid-thirties. Several British clinics offer women in their twenties and thirties the option of storing their eggs, and more than 100 have done so.

Dr Lockwood said that a third of her patients had the procedure for social reasons, a third have had cancer treatment, and another third used it for ethical reasons. Freezing costs £2,000 to £3,000, plus an annual fee for storage. “Many women are clear they want to be a mother one day, and aren’t in a position to do that now. That’s the group we can help,” she said.

Explore Health

• Expert Advice

• Health Features

• Mental Health

• Alternative Medicine

• Child Health

• Health Club