title: First-trimester examination of fetal nasal bone in the Chinese population.
abstract: OBJECTIVE
  Absence of the nasal bone in fetuses with trisomy 21 is a potential ultrasound marker for Down syndrome from the first trimester onwards. Racial differences in fetal nasal bone length have been reported. There was no reference range for the first-trimester fetal nasal bone length (NBL) in the Chinese population.
  
  
  METHODS
  From January 2002 to February 2005, we investigated the reference range of NBL in 2169 singleton fetuses whose parents were Chinese with normal pregnancy outcome. Ultrasound measurements of NBL were performed on a midsagittal plane at 12-14 weeks' gestation.
  
  
  RESULTS
  The nasal bone length measurement showed a significant increase with gestational age (GA) (p < 0.05). A linear relationship between nasal bone length and gestational age (NBL = -3.3462 x GA + 0.627, R(2) = 0.30, p < 0.001) as well as a linear relationship between nasal bone length and crown-rump length (CRL) (NBL = 0.3741 x CRL + 0.284, R(2) = 0.30, P < 0.001) was established.
  
  
  CONCLUSIONS
  The measurement of nasal bone length was feasible in the first trimester. The reference range of NBL in normal Chinese fetuses in the first-trimester of pregnancy was established. This formed a basis for further study on the use of fetal nasal bone measurement in the screening for aneuploidy in the Chinese population.
authors.affiliation: Department of Obstetrics and Gynaecology, The University of Hong Kong, Queen Mary Hospital, Hong Kong, China. Chenm@hkusua.hku.hk
authors.forename: Min
authors.initials: M
authors.lastname: Chen
authors.forename: Chin Peng
authors.initials: CP
authors.lastname: Lee
authors.forename: Rebecca
authors.initials: R
authors.lastname: Tang
authors.forename: Ben
authors.initials: B
authors.lastname: Chan
authors.forename: Chun Quan
authors.initials: CQ
authors.lastname: Ou
authors.forename: Mary Hoi Yin
authors.initials: MH
authors.lastname: Tang
mesh_terms: D000293:Adolescent; D000328:Adult; D002681:China; D005260:Female; D047109:Fetal Development; D006801:Humans; D009295:Nasal Bone / Q000000981:diagnostic imaging* / Q000196:embryology*; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D012016:Reference Values; D016216:Ultrasonography, Prenatal / Q000379:methods*