title: Fetal nasal bone length in the second trimester: comparison between population groups from different ethnic origins.
abstract: OBJECTIVE
  To compare normal ranges of ultrasonographically measured fetal nasal bone length in the second trimester between different ethnic groups.
  
  
  METHODS
  A prospective, non-interventional study in order to establish normal ranges of fetal nasal bone length in the second trimester in a Greek population was conducted in 1220 singleton fetuses between 18 completed weeks and 23 weeks and 6 days of gestation. A literature search followed in order to identify similar studies in different population groups. Fetal nasal bone length mean values and percentiles from different population groups were compared.
  
  
  RESULTS
  Analysis of measurements in the Greek population showed a linear association, i.e., increasing nasal bone length with increasing gestational age from 5.73 mm at 18 weeks to 7.63 mm at 23 weeks. Eleven studies establishing normal ranges of fetal nasal bone length in the second trimester were identified. Comparison of fetal nasal bone length mean values between the 12 population groups showed statistically significant differences (P<0.0001).
  
  
  CONCLUSIONS
  Normal ranges of fetal nasal bone length in the second trimester vary significantly between different ethnic groups. Hence, distinct ethnic nomograms of fetal nasal bone length in the second trimester should be used in a given population rather than an international model.
authors.forename: Panayiota
authors.initials: P
authors.lastname: Papasozomenou
authors.forename: Apostolos P
authors.initials: AP
authors.lastname: Athanasiadis
authors.forename: Menelaos
authors.initials: M
authors.lastname: Zafrakas
authors.forename: Eleftherios
authors.initials: E
authors.lastname: Panteris
authors.forename: Aristoteles
authors.initials: A
authors.lastname: Loufopoulos
authors.forename: Efstratios
authors.initials: E
authors.lastname: Assimakopoulos
authors.forename: Basil C
authors.initials: BC
authors.lastname: Tarlatzis
mesh_terms: D005006:Ethnicity; D005260:Female; D005865:Gestational Age; D006115:Greece; D006801:Humans; D009295:Nasal Bone / Q000000981:diagnostic imaging*; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011446:Prospective Studies; D044469:Racial Groups; D012016:Reference Values; D016216:Ultrasonography, Prenatal