An estimated further 400 babies who are tested but found not to have the condition die as a result of a miscarriage, say Prof. Sue Buckley and Frank Buckley of Down Syndrome Education International (DownsEd), a charity that opposes genetic screening and the abortion of babies who test positive.[..]

The DownsEd report says that, according to the best available evidence, the risk of pregnancy loss resulting from amniocentesis is 1% (one child in 100) and in the case of CVS, 2% (one child in 50).

But it also notes other factors, such as the level of experience of those carrying out the tests: "Studies have observed loss rates following amniocentesis that are 6 to 8 times higher among less experienced practitioners than among experienced practitioners."

Moreover, the study estimates that 95% of "positive" screens (6,660 out of 7,000) actually are wrong, meaning that a far higher number of women go on to have the invasive – and potentially risky – diagnostic tests than necessary.

The authors say they "do not consider a diagnosis of Down syndrome to be a sufficient reason to justify termination and so disagree with the basic premise for prenatal screening for Down syndrome. Harming babies who do not have Down syndrome in the process seems to us unjustifiable."