There has been a sharp rise in the last 20 years in the amount of babies diagnosed with Down's Syndrome as women choose to delay motherhood.
A 71% rise in the number of babies with the condition, standing at 1,843 diagnoses in 2007/8, has seen the number of babies born with the disease fall because screening procedures are move advanced, and abortion procedures often employed.
Live births of Down's babies defied the rise to fall by 1% to 743, which equates to 1.08 for every 1,000 births, from last year's figures.
If screening had not taken place, the number of babies born with Down's would have risen by 48%.
Experts from Queen Mary, University of London, analysed data from the Down's register for England and Wales for the study, published online in the British Medical Journal (BMJ).
Joan Morris, professor of medical statistics at Queen Mary, who led the study, said: "What we're seeing here is a steep rise in pregnancies with Down's syndrome but that is being offset by improvements in screening.
"It was thought that these improvements would lead to a decrease in the number of births with Down's syndrome. However due to increases in maternal age this has not occurred."
"I was indeed surprise with the increase in Down's birth having early detection measures including a/n intervention technology where exactly has early prevention gone wrong surely the purpose of preconception and a/n screening and tests were to detect abnormalities early and to give choice if problems have occurred. What is the next step should there be more research in genetic testing preconceptually?" - V Henry, London