Pregnant females undergoing tests, like CVS or amniocentesis, for the detection of the Down’s syndrome, are at higher risk of miscarriages.

As per a study conducted, by the Charity Down Syndrome Education International, around two babies without Down's syndrome, were lost in the process of preventing the birth of three with Down's. Besides CVS, questions have been raised, on the risk involved on pregnant women, undergoing ultrasound scan.

CVS or amniocentesis involves the insertion of instruments which leads to risk of miscarriage - up to one in 100 for amniocentesis and one in 50 for CVS. 

Prof Kypros Nicola ides (King's College Hospital, London) said, "It is completely unacceptable that to detect 600, 700 or 800 foetuses with Down's, we must have the loss of 400 more or less normal babies."