title: Maternal ethnic origin and fetal nasal bones at 11-14 weeks of gestation.
abstract: OBJECTIVE
  Failure to visualise the fetal nasal bones at 11-14 weeks of gestation is associated with a significant increase in the risk for trisomy 21. However, it is not known whether the ethnic origin of the mother has any effect on the fetal profile and the prevalence of this marker.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  London Teaching Hospital.
  
  
  METHODS
  Four thousand and four hundred and ninety-two consecutive fetuses undergoing routine first trimester ultrasound scanning at 11-14 weeks of gestation in a multiethnic population.
  
  
  METHODS
  Examination of the nasal bones was attempted in the fetuses.
  
  
  METHODS
  Rate of visualisation of the fetal nasal bones.
  
  
  RESULTS
  Five hundred fetuses were excluded from the analysis because of chromosomal abnormalities or a technically unsatisfactory examination. In the remaining 3992 fetuses, the maternal ethnic origin was African in 13.0%, Asian in 15.3% and Caucasian in 66.0%. Compared with Caucasians, the failure to visualise the fetal nasal bones was significantly higher in women of African (P= 0.0001) but not Asian origin (P= 0.24). A multivariable logistic regression model showed that having a mother of African origin is still significantly associated with an increased likelihood of absent fetal nasal bones compared with Caucasians (odds ratio 2.33), even after correcting for maternal age, parity and crown-rump length.
  
  
  CONCLUSIONS
  There is a significant difference in the rate of visualisation of the fetal nasal bones in the first trimester in mothers of different ethnic origin. This suggest that corrections for maternal ethnicity will be required to ensure equity of fetal nasal bone screening in multiracial populations. Whether corrections are required for the father's ethnic origin remains to be determined.
authors.affiliation: Fetal Medicine Unit, Academic Department of Obstetrics and Gynaecology, St George's Hospital Medical School, London, UK.
authors.forename: Federico
authors.initials: F
authors.lastname: Prefumo
authors.forename: Shanthi
authors.initials: S
authors.lastname: Sairam
authors.forename: Amarnath
authors.initials: A
authors.lastname: Bhide
authors.forename: Leonie
authors.initials: L
authors.lastname: Penna
authors.forename: Brian
authors.initials: B
authors.lastname: Hollis
authors.forename: Baskaran
authors.initials: B
authors.lastname: Thilaganathan
mesh_terms: D000328:Adult; D000349:Africa / Q000208:ethnology; D000704:Analysis of Variance; D001208:Asia / Q000208:ethnology; D018568:Crown-Rump Length; D004314:Down Syndrome / Q000000981:diagnostic imaging / Q000208:ethnology*; D005260:Female; D006801:Humans; D009295:Nasal Bone / Q000002:abnormalities* / Q000000981:diagnostic imaging; D010298:Parity; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011446:Prospective Studies; D012044:Regression Analysis; D012307:Risk Factors; D016216:Ultrasonography, Prenatal / Q000592:standards*