title: First-trimester sonographic screening for Down syndrome.
authors.forename: Naomi
authors.initials: N
authors.lastname: Greene
mesh_terms: D004314:Down Syndrome / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D009333:Neck / Q000000981:diagnostic imaging / Q000196:embryology; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D016216:Ultrasonography, Prenatal