RT Journal Article SR Electronic T1 Surge in Down syndrome prenatal testing anticipated JF Canadian Medical Association Journal JO CMAJ FD Canadian Medical Association SP cmaj.109-4170 DO 10.1503/cmaj.109-4170 A1 Collier, Roger YR 2012 UL http://www.cmaj.ca/content/early/2012/04/23/cmaj.109-4170.abstract AB