title: Finding the most accurate method to measure head circumference for fetal weight estimation.
abstract: OBJECTIVE
  Accurate measurement of fetal head biometry is important for fetal weight estimation (FWE) and is therefore an important prognostic parameter for neonatal morbidity and mortality and a valuable tool for determining the further obstetric management. Measurement of the head circumference (HC) in particular is employed in many commonly used weight equations. The aim of the present study was to find the most accurate method to measure head circumference for fetal weight estimation.
  
  
  METHODS
  This prospective study included 481 term pregnancies. Inclusion criteria were a singleton pregnancy and ultrasound examination with complete fetal biometric parameters within 3 days of delivery, and an absence of structural or chromosomal malformations. Different methods were used for ultrasound measurement of the HC (ellipse-traced, ellipse-calculated, and circle-calculated). As a reference method, HC was also determined using a measuring tape immediately after birth. FWE was carried out with Hadlock formulas, including either HC or biparietal diameter (BPD), and differences were compared using percentage error (PE), absolute percentage error (APE), limits of agreement (LOA), and cumulative distribution.
  
  
  RESULTS
  The ellipse-traced method showed the best results for FWE among all of the ultrasound methods assessed. It had the lowest median APE and the narrowest LOA. With regard to the cumulative distribution, it included the largest number of cases at a discrepancy level of ±10%. The accuracy of BPD was similar to that of the ellipse-traced method when it was used instead of HC for weight estimation.
  
  
  CONCLUSIONS
  Differences between the three techniques for calculating HC were small but significant. For clinical use, the ellipse-traced method should be recommended. However, when BPD is used instead of HC for FWE, the accuracy is similar to that of the ellipse-traced method. The BPD might therefore be a good alternative to head measurements in estimating fetal weight.
authors.affiliation: Department of Obstetrics and Gynecology, University Medical Centre Mannheim, Heidelberg University, Mannheim, Germany.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Schmidt
authors.affiliation: Department of Obstetrics and Gynecology, University Medical Centre Mannheim, Heidelberg University, Mannheim, Germany; Department of Obstetrics and Gynecology, Stadtklinik Frankenthal, Frankenthal, Germany.
authors.forename: Dunja
authors.initials: D
authors.lastname: Temerinac
authors.affiliation: Department of Obstetrics and Gynecology, Stadtklinik Frankenthal, Frankenthal, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Bildstein
authors.affiliation: Department of Obstetrics and Gynecology, University Medical Centre Mannheim, Heidelberg University, Mannheim, Germany.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Tuschy
authors.affiliation: Department of Obstetrics and Gynecology, University Medical Centre Mannheim, Heidelberg University, Mannheim, Germany.
authors.forename: Jade
authors.initials: J
authors.lastname: Mayer
authors.affiliation: Department of Obstetrics and Gynecology, University Medical Centre Mannheim, Heidelberg University, Mannheim, Germany; Department of Obstetrics and Gynecology, Stadtklinik Frankenthal, Frankenthal, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Sütterlin
authors.affiliation: Department of Obstetrics and Gynecology, Klinikum Pforzheim, Pforzheim, Germany.
authors.forename: Jörn
authors.initials: J
authors.lastname: Siemer
authors.affiliation: Department of Obstetrics and Gynecology, University Medical Centre Mannheim, Heidelberg University, Mannheim, Germany; Department of Obstetrics and Gynecology, Erlangen University Hospital, Erlangen, Germany. Electronic address: sven.kehl@gmail.com.
authors.forename: Sven
authors.initials: S
authors.lastname: Kehl
mesh_terms: D000328:Adult; D002508:Cephalometry; D005260:Female; D020567:Fetal Weight; D006257:Head / Q000000981:diagnostic imaging*; D006801:Humans; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D011446:Prospective Studies; D016216:Ultrasonography, Prenatal / Q000379:methods*
keywords: Biparietal diameter; Fetal weight estimation; Head circumference; Measurement; Ultrasound