New research has demonstrated that over 95 per cent of cases of Down syndrome can now be detected very early in pregnancy.
The finding comes from a study of more than 38,000 pregnant women in the US led by an Irish professor of obstetrics and gynaecology, Prof Fergal Malone.
His research team found specialised ultrasound and blood tests combined can detect over 95 per cent of cases of Down syndrome as early as 10 to 12 weeks gestation for all pregnant women.
Prof Malone, of Royal College of Surgeons in Ireland and the Rotunda Hospital, said pregnant women often think there is no hurry about being assessed. Many present for the first time at 15-16 weeks when they could be screened for Down syndrome and other foetal abnormalities at 10-11 weeks.
They can also be given an accurate due date at this stage and most will go away reassured they can expect to give birth to a healthy baby.
He said the tests were more accurate at 11 weeks. "You will have missed the boat at 15 weeks," he said.
Prof Malone said Down syndrome was one of the most common genetic causes of intellectual impairment and concern regarding this condition caused considerable anxiety for many pregnant women, especially among those aged 35 years and over. However, he said the combined screening tests should now be offered to all pregnant women regardless of their age as cases of Down syndrome were also found in under 35s.
He said it still happened that some women in the Republic did not find out their child had Down syndrome until it was born. There was a lot to be gained, he said, from having the diagnosis earlier as it prepared couples for what was ahead and also ensured arrangements could be made for the child to have heart or other surgery within days of birth if this was required, and it often was.
He said he now offered ultrasound and blood test screening to all women as did several of his colleagues. But for it to be provided at all centres more experts would have to be trained in the ultrasound technique.
He hoped the results of the study would "spur people" on to address these issues. "The scan measures the skin thickness at the back of the baby's neck and a fraction of a millimetre off can give a very inaccurate result," he said.
He advises any woman wishing to avail of this type of screening to speak to her GP, her midwife or her obstetrician and if they cannot provide screening they may be able to direct her to somebody who can.
The traditional test for Down syndrome, CVS or amniocentesis, carries a small risk of miscarriage. "This new research shows that the vast majority of women, both old and young, can avoid amniocentesis by using ultrasound and blood tests which pose no risk to the pregnancy and give reassurance to the patient early on," he added.
The research will be published today in the New England Journal of Medicine. It was led by Prof Malone while at Columbia University, New York, and subsequently at RCSI, upon his appointment there earlier this year. He is a graduate of UCD.