title: Contingent screening for Down syndrome.
authors.forename: Anne M
authors.initials: AM
authors.lastname: Summers
authors.forename: Tianhua
authors.initials: T
authors.lastname: Huang
authors.forename: Chris
authors.initials: C
authors.lastname: Meier
authors.forename: Sandra A
authors.initials: SA
authors.lastname: Farrell
mesh_terms: D004314:Down Syndrome / Q000175:diagnosis*; D005260:Female; D006801:Humans; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*; D012306:Risk