title: Estimations of gestational age and screening for Down's syndrome.
authors.forename: T M
authors.initials: TM
authors.lastname: Reynolds
authors.forename: M D
authors.initials: MD
authors.lastname: Penney
mesh_terms: D002508:Cephalometry; D004314:Down Syndrome / Q000175:diagnosis*; D005315:Fetal Diseases / Q000175:diagnosis*; D005865:Gestational Age; D006801:Humans; D010294:Parietal Bone / Q000033:anatomy & histology; D011296:Prenatal Diagnosis; D012307:Risk Factors