title: Impact of replacing Chinese ethnicity-specific fetal biometry charts with the INTERGROWTH-21(st) standard.
abstract: OBJECTIVE
  To assess the impact of adopting the INTERGROWTH-21(st) biometry standards in a Chinese population.
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  A teaching hospital in Hong Kong.
  
  
  METHODS
  A total of 10 527 Chinese women with a singleton pregnancy having a second- or third-trimester fetal anomaly or growth scan between January 2009 and June 2014.
  
  
  METHODS
  Z-scores were derived for fetal abdominal circumference (AC), head circumference (HC), and femur length (FL) using the INTERGROWTH-21(st) and Chinese biometry standards. Pregnancies with aneuploidy, structural or skeletal abnormalities, or that developed pre-eclampsia were excluded. Z-scores were stratified as <2.5th, <5th, <10th, >90th, >95th, or >97.5th percentile. Birthweight centile, adjusted for gestation and gender, was categorised as ≤3rd, 3rd to ≤5th, 5th to ≤10th, and >10th. Pairwise comparison and the McNemar test were performed to assess biometry Z-score differences and concordance between the INTERGROWTH-21(st) and Chinese standards.
  
  
  METHODS
  The sensitivity of both the local and INTERGROWTH-21(st) AC standards to identify pregnancies that were small-for-gestational-age (SGA) was assessed.
  
  
  RESULTS
  INTERGROWTH-21(st) AC, HC, and FL Z-scores were significantly lower than those obtained using our local reference for AC, HC, and FL (P < 0.0001 for all). The proportion of fetuses with biometry in the <2.5th, <5th, <10th, >90th, >95th, or >97.5th percentiles was statistically significant (P < 0.01 for all). A total of 1224 (15.5%) of the scans at 18-22 weeks of gestation had AC, HC, or FL below the 3rd percentile of the INTERGROWTH-21(st) standard.
  
  
  CONCLUSIONS
  Adopting the INTERGROWTH-21(st) standard would lead to a significant number of fetuses being at risk of misdiagnosis for small fetal size, particularly when using HC and FL measures.
  
  
  CONCLUSIONS
  INTERGROWTH-21(st) biometry assessment in Chinese leads to fetuses being at risk of misdiagnosis of small fetal size.
authors.affiliation: Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China.
authors.forename: Yky
authors.initials: Y
authors.lastname: Cheng
authors.affiliation: Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China.
authors.forename: T Y
authors.initials: TY
authors.lastname: Leung
authors.affiliation: Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China.
authors.forename: Tth
authors.initials: T
authors.lastname: Lao
authors.affiliation: Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China.
authors.forename: Y M
authors.initials: YM
authors.lastname: Chan
authors.affiliation: Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China. daljit@cuhk.edu.hk.
authors.forename: D S
authors.initials: DS
authors.lastname: Sahota
mesh_terms: D000328:Adult; D001699:Biometry / Q000295:instrumentation*; D001724:Birth Weight; D003951:Diagnostic Errors; D005006:Ethnicity; D005260:Female; D047109:Fetal Development; D005317:Fetal Growth Retardation / Q000175:diagnosis*; D020567:Fetal Weight; D057238:Growth Charts; D006257:Head / Q000000981:diagnostic imaging* / Q000196:embryology; D006723:Hong Kong; D006801:Humans; D007236:Infant, Small for Gestational Age; D000069342:Medical Overuse; D011237:Predictive Value of Tests; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D012015:Reference Standards; D012189:Retrospective Studies; D018570:Risk Assessment; D016216:Ultrasonography, Prenatal / Q000592:standards
keywords: Chinese; INTERGROWTH-21st; fetal biometry; pregnancy; small-for-gestational-age; ultrasound measurements