SCIENTISTS ARE testing a revolutionary IVF technique that initial results show is three times more successful than current methods. By screening eggs for genetic abnormalities before implanting them back into patients a U.S. trial pushed the IVF success rate above 70 per cent.

The researchers said the technique could be particularly beneficial for older women, whose eggs are more likely to have genetic abnormalities.

"It has the prospect to change the way we do IVF for certain groups of patients and it is very exciting," said Simon Fishel at the Care fertility clinic in Nottingham, England, which is carrying out a U.K. trial of the technique.

Robin Lovell-Badge, an expert in assisted reproduction at the National Institute for Medical Research in London, hailed the technique as potentially ``a significant jump''.

Checking egg or embryo

The technique could mean that couples will have to undergo fewer IVF attempts before giving birth to a healthy baby.

The technique, which is called comparative genomic hybridisation (CGH), works by checking an egg or an embryo fertilised in the lab for abnormalities in its chromosomes. One of these abnormalities causes Down's syndrome, but many more result in miscarriage, even before the woman realises she is pregnant.

"At least half of a couples' embryos have a chromosome abnormality," said Dr Fishel.

"The problem is that if you have lots of embryos and we're only allowed to put two back, you don't know which two to choose.

If we can choose ones that are more likely to be viable we should in theory improve the pregnancy rate, reduce the miscarriage rate and overall have a much higher live birth rate."

Conflicting results

It is possible to do chromosome screening at present, but the technique has yielded conflicting results.

New Scientist magazine reported that Geoffrey Sher at the Sher Institute for Reproductive Medicine in Las Vegas and his team recruited 41 infertile women with an average age of 37.5.

Egg screening

They screened their eggs — or donor eggs in 13 cases — for abnormalities using CGH and 35 of the women produced at least one embryo after IVF that could be implanted.

Of these, 28 became pregnant, two miscarried, 18 have given birth and eight are expected to imminently.If these pregnancies are successful the team will have achieved a success rate of 74 per cent.

Less for older women

In the U.K., for example, even women over 35, who have the best chance of success, experience a 28 per cent success rate from traditional IVF.In 40 to 42-year-old women that drops to 11 per cent in the U.K. The study is published in the journal Fertility and Sterility.—

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