Two healthy babies miscarry following testing for Down's Syndrome for every three foetuses diagnosed with the condition in the womb, according to new research.
Two healthy babies miscarry following testing for Down's Syndrome for every three foetuses diagnosed with the condition in the womb, according to new research.
The ratio was condemned as "completely unacceptable" by one of Britain's leading foetal health experts, who called for the speedy introduction of better screening of mothers-to-be to reduce reliance on the invasive tests which are blamed for miscarriages.
According to figures compiled by the Down Syndrome Education International charity, some 660 cases of the condition are detected by ante-natal testing in England and Wales each year, most of them leading to abortions. But 400 healthy babies are lost following the tests.
DSEI chief executive Frank Buckley told Channel 4 News: "Around 400 babies without Down's Syndrome being lost in the process of preventing the birth of 660 babies with Down's Syndrome - that's around two babies without for every three babies with.
"I think that's a shocking ratio."
The charity has written to the Government asking for a thorough reappraisal of the purpose, performance and safety of the screening programme.
Around 600,000 women a year in England and Wales are offered screening for Down's, often by ultrasound scan. However, this does not detect all cases of the condition and inevitably results in a sizeable number of "false positives".
Those deemed most at risk as a result of the scans are generally offered diagnostic testing by either amniocentesis or CVS, which are more accurate but involve the insertion of instruments into the vulva, with a small risk of miscarriage - up to one in 100 for amniocentesis and one in 50 for CVS.
The National Institute for Health and Clinical Excellence this year recommended that all pregnant women should receive "combined screening", which involves blood tests as well as scans and cuts the number of false positives without risk to the baby.
Professor Kypros Nicolaides, of King's College Hospital in London, an expert in foetal medicine, said the combined screening should be introduced as a matter of urgency.
He told C4N: "It is completely unacceptable that in order to detect 600, 700 or 800 foetuses with Down's Syndrome, we must tolerate the intolerable loss of 400 - more or less - normal babies.
"Our aim must be to improve the detection of foetuses with Down's in those women who want to have a test and dramatically reduce the number of normal babies that are lost as part of the process of screening and diagnosis."
Combined screening can "dramatically reduce the number of unnecessary invasive tests and substantially reduce the detection rate", Prof Nicolaides said.
Mr Buckley said that DSEI's figures, due to be published later this week, were obtained from "national registry data and actual recorded pre-natal diagnoses".
He added: "We have then taken the performance of screening tests that are in use today from large studies involving multiple hospitals, carefully controlled and published in leading scientific journals, to obtain the ratios we use to make our estimate."
The Department of Health said in a statement: "The primary aim of ante-natal screening for Down's Syndrome is to offer women information about their pregnancy so they can make their own informed decision based on the latest evidence from the National Screening Committee and Nice.
"The national programme supports the most effective test in terms of both the detection rate and the aim of lowering the screen positive rate in order to minimise the number of diagnostic tests.
"The screening programme supports consistent training and information for staff. To ensure that screening is both effective and safe for all women, a quality assurance system has been set up."
