Page last updated at 23:02 GMT, Wednesday, 11 June 2008 00:02 UK

Fertility DNA checks discouraged

An eight-cell embryo
Embryos can be screened for genetic disorders

Embryo chromosome screening should not be offered to women to improve their chances of an IVF baby, expert guidelines say.

The British Fertility Society says there is no evidence it improves the chance of success, or cuts the risk of miscarriage for older women.

However, a leading doctor offering the technique insisted it was worthwhile and could prevent miscarriages.

Embryo screening to prevent inherited diseases is unaffected by the guidance.

It is clear there is no compelling evidence that PGS improves the clinical pregnancy rate, live birth rate, or that it reduces the miscarriage rate
Professor Richard Anderson
British Fertility Society

The technique involved - preimplantation genetic screening (PGS) - takes a single cell from the multiple embryos created outside the body as part of fertility treatment.

The cells are checked for abnormalities called aneuploidies, which involve missing or extra copies of chromosomes.

If found to have them, that embryo is not selected to be put back into the woman.

It is suggested that since an embryo with these abnormalities might be more likely to fail to implant or grow correctly, not using one could either make pregnancy more likely, or reduce the chances of a pregnancy failing within the first trimester.

Older women are more likely to produce embryos with aneuploidies.

The UK authority, the Human Fertilisation and Embryology Authority, currently allows clinics to use it to treat women who are aged 35 and over, those who have had several failed IVF cycles, or suffer from recurrent miscarriage.

It is not a cheap technique, adding well over 1,000 to the cost of every cycle of IVF.

'No compelling evidence'

However, the British Fertility Society said it had looked closely at studies, and found no evidence of any benefits in any of the patient groups allowed to be offered the treatment.


Its guidelines say that PGS should only be offered as part of further clinical trials.

Professor Richard Anderson, who wrote the guidelines, said that patients should be told by clinics that there was no evidence it worked.

"We want to ensure that all women receive the safest and most effective treatment when undergoing fertility procedures.

"It is clear there is no compelling evidence that PGS improves the clinical pregnancy rate, live birth rate, or that it reduces the miscarriage rate."

The guidelines do not discourage the use of preimplantation genetic diagnosis (PGD), a technique which has allowed a parent suffering from or carrying the genes for serious hereditary diseases, such as cystic fibrosis, to conceive a child known to be free of the condition.

Professor Alan Handyside, from the Bridge Centre in London, which offers the technique to between 10% and 20% of the couples it treats, said he feared that the guidance would prompt the HFEA to stop licensing clinics to provide it.

He said that he was convinced that screening embryos was a worthwhile exercise for many couples.

"By selecting the normal embryos, you can reduce the chance of a miscarriage, which, for a woman in her 40s, can mean a wait of a year before she is ready to try again.

"It may not increase the live birth rate, but it could reduce the amount of cycles needed to produce a live birth."

He said that in some cases, screening could actually help couples decide not to implant any embryos, if all were found to be abnormal.

A spokesman for the HFEA said that it was already reviewing the efficacy of PGS, and that the guidance provided by the British Fertility Society would play a role in that process.


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