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Last Updated: Tuesday, 17 June, 2003, 11:11 GMT 12:11 UK
Success for embryo screening
The pregnancy is in its early stages
A technique that could revolutionise IVF for older women is producing successful pregnancies in the UK.

Although "aneuploidy screening" has been offered for some time in the US and some European countries, it was only given the go-ahead in Britain last year.

The technique involves checking IVF embryos for signs of genetic abnormalities by taking a single cell for analysis.

These abnormalities are blamed for many cases of recurrent miscarriage, and might be the cause of "unexplained infertility" in many other women.

Nature produces a high percentage of abnormal embryos and simply looking down a microscope cannot detect these
Dr Simon Fishel, director, CARE clinic
As women get older, the chances of producing abnormal embryos increases steadily - and experts believe that screening might be a way to improve the fertility of older women.

The CARE at the Park clinic near Nottingham is among the first to use the new technique.

Eight weeks

Among the first patients is a 42-year-old woman who not only had a prior history of recurrent miscarriage, but, in recent years, had never even managed a positive pregnancy test.

Doctors suspected that these genetic abnormalities were preventing fertilised embryos from even implanting in the womb.

She is now eight weeks pregnant, and although miscarriage risk is highest until the 12-week mark, doctors are encouraged by the fact that a normal foetal heart has been detected on two ultrasound scans, and that other organs appear to be developing normally.

Dr Simon Fishel, the clinic's director, said that out of six of the woman's embryos screened, four had distinct abnormalities, so the other two were used.

He said: "Nature produces a high percentage of abnormal embryos and simply looking down a microscope cannot detect these.

"Using this technology we were able to select the only two chromosomally normal embryos for transfer to the womb."

Success rate

He said that the technique could detect up to 50% of chromosomal abnormalities in embryos, and up to 70% of those believed to cause miscarriage in the first 12 weeks of pregnancy.

He said that the technique could also screen for chromosomal disorders such as Down's syndrome and Edward's syndrome.

"Ante-natal screening is routinely accepted, but should a problem arise, couples may face a termination well into pregnancy.

"Screening an embryo for high-risk couples could help prevent that happening."

Only two, and very exceptionally three embryos at most can be transferred back into a woman undergoing IVF in the UK to reduce the chance of multiple births.

Embryologists tend to pick the embryos which are growing at the best rate, or even those which have a better appearance under the microscope, and while there is some evidence that this technique improves results, it is far from an exact science.

Three licences to carry out the procedure have so far been granted - the other two involve London-based clinics.

The BBC's Gill Higgins
"Doctors say many women could benefit"

Go-ahead for miscarriage tests
02 Sep 02  |  Health
IVF: One woman's story
30 Aug 02  |  Health
Male fertility gene found
22 May 03  |  Health

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