title: Revisiting first-trimester fetal biometry.
abstract: BACKGROUND
  Although advances in ultrasound have facilitated the diagnosis of fetal abnormalities in the first trimester, fetal biometry at this stage of pregnancy remains underused in prenatal diagnosis. We hypothesized that charts which directly correlate measurements to crown-rump length (CRL) could be more accurate than those based on gestational age (GA) derived from CRL measurement. The aim of this study was to construct CRL-based biometric charts.
  
  
  METHODS
  Measurements of biparietal diameter (BPD), head circumference (HC) and abdominal circumference (AC) were prospectively collected from 939 normal singleton fetuses. Charts and predictive equations were constructed from data obtained from pregnancies in which the CRL was between 45 and 84 mm and for which the outcome was normal.
  
  
  RESULTS
  Measurements of BPD, HC and AC from 880 fetuses who met the criteria were correlated with CRL and used to construct charts and predictive equations. The standard error of estimates using CRL was significantly lower than that using GA in all cases.
  
  
  CONCLUSIONS
  First-trimester growth charts and predictive equations based on CRL instead of GA are more accurate. They might have a role in quality control of first-trimester ultrasound examination and may help in the diagnosis of fetal conditions that involve early growth abnormalities.
authors.affiliation: Service de Gynécologie-Obstétrique, Centre Hospitalier Intercommunal de Poissy-St Germain, Poissy, France.
authors.forename: L J
authors.initials: LJ
authors.lastname: Salomon
authors.forename: J P
authors.initials: JP
authors.lastname: Bernard
authors.forename: M
authors.initials: M
authors.lastname: Duyme
authors.forename: A
authors.initials: A
authors.lastname: Dorion
authors.forename: Y
authors.initials: Y
authors.lastname: Ville
mesh_terms: D000005:Abdomen / Q000196:embryology; D000328:Adult; D018568:Crown-Rump Length; D005314:Embryonic and Fetal Development; D005260:Female; D005333:Fetus / Q000033:anatomy & histology*; D005865:Gestational Age; D006257:Head / Q000196:embryology; D006801:Humans; D008875:Middle Aged; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D012016:Reference Values; D016216:Ultrasonography, Prenatal