title: [Distribution and normal reference range of fetal nuchal translucency thickness in Kunming pregnant women in the first trimester].
abstract: OBJECTIVE
  To establish the normal reference range of fetal nuchal translucency (NT) thickness in Kunming Chinese pregnant women in the first trimester.
  
  
  METHODS
  The study samples comprised of 1790 Kunming pregnant women who attended antenatal visit in the first trimester in the First Affiliated Hospital of Kunming Medical University. The general information including maternal date of birth, past pregnant history and other related conditions were recorded. The crown rump length (CRL) and NT thickness at 11 - 13(+6) gestational weeks were measured according to guidelines from Fetal Medicine Foundation (FMF).
  
  
  RESULTS
  The total 1790 of normal fetuses was recruited for final analysis. The mean and median values of CRL were (59.6 ± 9.2) mm and 58.3 mm, respectively. The mean and median values of NT thickness were (1.7 ± 0.5) mm and 1.7 mm, respectively. While the CRL were at between 45.0 - 54.9 mm, 55.0 - 64.9 mm, 65.0 - 74.9 mm and 75.0 - 84.0 mm, the corresponding values of NT thickness were 1.0 mm, 1.3 mm, 1.5 mm, 1.5 mm at the 5(th) percentile and 2.0 mm, 2.5 mm, 2.7 mm, 2.9 mm at the 95(th) percentile, respectively, and the corresponding medial values of NT thickness were 1.4 mm, 1.7 mm, 2.0 mm, 2.0 mm, respectively. The NT thickness had no relationship with maternal age (P > 0.05). The mean value of NT thickness was (1.8 ± 1.1) mm in male fetuses. The mean value of NT thickness was (1.7 ± 0.6) mm in female fetuses. The NT thickness in male fetuses was significantly thicker than that of females (P = 0.001).
  
  
  CONCLUSIONS
  The present study established a reference range of normal fetal NT thickness corresponding with CRL in early pregnancy with reliable FMF quality control.
authors.affiliation: Department of Obstetrics and Gynecology, the First Affiliated Hospital of Kunming Medical University, Kunming 650032, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Sun
authors.forename: Jing
authors.initials: J
authors.lastname: Xu
authors.forename: Shun-qin
authors.initials: SQ
authors.lastname: Hu
authors.forename: Min
authors.initials: M
authors.lastname: Chen
authors.forename: Run-mei
authors.initials: RM
authors.lastname: Ma
authors.forename: Tze Kin
authors.initials: TK
authors.lastname: Lau
authors.forename: Lan
authors.initials: L
authors.lastname: Zhang
authors.forename: Xue
authors.initials: X
authors.lastname: Xiao
authors.forename: Yuan
authors.initials: Y
authors.lastname: Qian
authors.forename: Zhi
authors.initials: Z
authors.lastname: Guo
mesh_terms: D000328:Adult; D002681:China; D018568:Crown-Rump Length; D004314:Down Syndrome / Q000175:diagnosis / Q000000981:diagnostic imaging*; D005260:Female; D005333:Fetus / Q000033:anatomy & histology*; D005865:Gestational Age; D006801:Humans; D048208:Nuchal Translucency Measurement / Q000592:standards* / Q000706:statistics & numerical data; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D012016:Reference Values; D013997:Time Factors; D016216:Ultrasonography, Prenatal / Q000379:methods