title: Contingent screening for Down syndrome.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Wald
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Bestwick
authors.forename: Jacob A
authors.initials: JA
authors.lastname: Canick
mesh_terms: D004314:Down Syndrome / Q000175:diagnosis; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008403:Mass Screening / Q000458:organization & administration*; D011247:Pregnancy