New screening technique developed in UK clinic may improve IVF success rate

Nadeem Shaikh

Progress Educational Trust

04 February 2009

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[BioNews, London]

A British fertility clinic has revealed they have developed a new method of screening eggs for IVF treatment. The CARE clinic in Nottingham, UK, has used the novel Comparative Genomic Hybridisation (CGH) method to assist a 41 year old woman to become pregnant.

Currently, only one in three IVF treatments will result in a successful pregnancy. Often this is because the egg has an abnormal number of chromosomes. In younger women, 50 per cent of their eggs will have some sort of chromosomal defect. This rises to 75 per cent in women over 40 years old.

This new method uses a laser to cut a hole at the edge of the egg to remove an extra copy of all the egg's chromosomes from something called the polar body. They can then be examined for abnormalities without disturbing the main genetic material of the egg itself.

This technique has been used before in the USA but was much slower. The UK clinic has reduced the time required from five days to just one, meaning the entire process can be completed in one round of treatment.

Because the screen takes place before fertilisation, it removes any potential moral conflict regarding the destruction of embryos found to have defects.

The first woman treated wishes to remain anonymous, but it is known that she is 41 years old, has had 13 previous IVF treatments and three miscarriages. Without the screen, her chances of a successful pregnancy were around seven per cent. In this round of treatment, nine eggs were tested, and only two were found to be viable. They were fertilised and implanted in the woman. She is now six months pregnant with one child.

Dr Simon Fishel is the director of the CARE fertility group. He says that 'In this country we have to reduce the incidence of multiple pregnancy and there's a big drive to put a single embryo back. That could reduce all women's chances of pregnancy but not if we choose the embryo that is most viable and has normal chromosomes.

'Ultimately we could reach the holy grail of one cycle of IVF, one egg, one embryo and one baby'.

Screening should increase rates of success for older, infertile women, and reduce incidence of miscarriages and IVF failure. The treatment costs £1,950 and is not available on the NHS. The British Fertility Society says that more studies are required.