The Institute of Obstetricians and Gynaecologists has said that while it is technically possible to diagnose chromosomal abnormality indicating that a foetus has Down syndrome before 12 weeks' gestation, the diagnosis can rarely or realistically be achieved within that timeframe.
In a statement issued by The Royal College of Physicians, the institute says it is misleading to suggest that disability will be eliminated by legislating for abortion on request up to 12 weeks.
However, it notes that the combined results of an ultrasound performed from 11 weeks' gestation onwards and a blood test taken from ten weeks onwards, can provide an assessment of the degree of risk of the chromosomal abnormality.
The institute's chairperson is Dr Peter Boylan, a long-time opponent of the Eighth Amendment.
It says it wants to inform the current public discussion about disability and the mooted repeal of the Eighth Amendment.
Last month, a special Oireachtas Committee recommended that abortion should be available on request up to 12 weeks' gestation.
The statement says that, in very rare cases, chromosomal abnormalities of the kind that lead to Down syndrome can be observed during the time women who are pregnant visit a midwife and have their initial basic scan and blood tests.
It says such a test, for example an ultrasound, raises "the possibility of an abnormality" rather than making a diagnosis.
It says the combined results of a scan and a blood test can provide an assessment of the degree of risk of a chromosomal abnormality before 12 weeks.
It says the second method of detecting the Down syndrome chromosome is a blood test to analyse the foetus' DNA in the mother's blood stream.
The institute says this test, which is sometimes called Harmony or Panorama, can be performed from nine weeks onwards.
But it adds that the samples have to be sent to the UK or the US for analysis and that results generally become available within two weeks.
Taking the statement's own figures into account, this means the results can become available from 11 weeks' gestation onwards.
The statement says the results of these screening tests are rarely available within 12 weeks' gestation, adding that they are not 100% reliable and that a further, diagnostic test must therefore, be performed.
The statement says that diagnosis of chromosomal abnormality, while technically possible, can rarely or realistically be achieved before twelve weeks.
"To suggest therefore that disability will be eliminated by enacting legislation in line with the recommendations of the Oireachtas committee is misleading," it concludes.
In a separate statement, the Royal College of Physicians of Ireland has told RTÉ News that it does not have a view on the Eighth Amendment to the Constitution.
Recent developments in testing for possible Down syndrome in the foetus were also addressed last year at the Citizens' Assembly by Dr Peter McParland, a colleague of Dr Peter Boylan's at the National Maternity Hospital in Dublin.
Last January, Dr McPartland told the gathering that non-invasive pre-natal testing could be done "as early as 10 weeks".
Today's statement from the Institute of Obstetricians and Gynaecologists, which is chaired by Dr Boylan, stated that the test could be performed from nine weeks onwards.
Dr McPartland also said that, although the test was very expensive initially, the price had come down considerably with a greater uptake from patients.
He predicted that it was likely to come down even further, making it more accessible to patients. Today the institute said the current price is €500 or more.
Dr McPartland also stated that the test is 99% accurate for diagnosing "common chromosome problems which would include Down's, Edwards and Patau syndrome".
Dr McPartland is a Consultant Obstetrician/Gynaecologist whose sub-specialty is Fetal Medicine.