title: [Advances in the mass screening of Down's syndrome in early and middle stages of pregnancy].
authors.forename: A
authors.initials: A
authors.lastname: Hang
authors.forename: X
authors.initials: X
authors.lastname: Chen
mesh_terms: D004314:Down Syndrome / Q000175:diagnosis* / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D011296:Prenatal Diagnosis; D014463:Ultrasonography