title: Down's syndrome screening: value of using free beta-hCG.
authors.forename: J
authors.initials: J
authors.lastname: Densem
authors.forename: N J
authors.initials: NJ
authors.lastname: Wald
mesh_terms: D006063:Chorionic Gonadotropin / Q000097:blood*; D018997:Chorionic Gonadotropin, beta Subunit, Human; D004314:Down Syndrome / Q000175:diagnosis*; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D010446:Peptide Fragments / Q000097:blood*; D011247:Pregnancy; D011296:Prenatal Diagnosis; D012016:Reference Values
chemical_list: D006063:Chorionic Gonadotropin; D018997:Chorionic Gonadotropin, beta Subunit, Human; D010446:Peptide Fragments