title: Systematic review of methodology used in ultrasound studies aimed at creating charts of fetal size.
abstract: BACKGROUND
  Reliable ultrasound charts are necessary for the prenatal assessment of fetal size, yet there is a wide variation of methodologies for the creation of such charts.
  
  
  OBJECTIVE
  To evaluate the methodological quality of studies of fetal biometry using a set of predefined quality criteria of study design, statistical analysis and reporting methods.
  
  
  METHODS
  Electronic searches in MEDLINE, EMBASE and CINAHL, and references of retrieved articles.
  
  
  METHODS
  Observational studies whose primary aim was to create ultrasound size charts for bi-parietal diameter, head circumference, abdominal circumference and femur length in fetuses from singleton pregnancies.
  
  
  METHODS
  Studies were scored against a predefined set of independently agreed methodological criteria and an overall quality score was given to each study. Multiple regression analysis between quality scores and study characteristics was performed.
  
  
  RESULTS
  Eighty-three studies met the inclusion criteria. The highest potential for bias was noted in the following fields: 'Inclusion/exclusion criteria', as none of the studies defined a rigorous set of antenatal or fetal conditions which should be excluded from analysis; 'Ultrasound quality control measures', as no study demonstrated a comprehensive quality assurance strategy; and 'Sample size calculation', which was apparent in six studies only. On multiple regression analysis, there was a positive correlation between quality scores and year of publication: quality has improved with time, yet considerable heterogeneity in study methodology is still observed today.
  
  
  CONCLUSIONS
  There is considerable methodological heterogeneity in studies of fetal biometry. Standardisation of methodologies is necessary in order to make correct interpretations and comparisons between different charts. A checklist of recommended methodologies is proposed.
authors.affiliation: Nuffield Department of Obstetrics and Gynaecology, University of Oxford, UK.
authors.forename: C
authors.initials: C
authors.lastname: Ioannou
authors.forename: K
authors.initials: K
authors.lastname: Talbot
authors.forename: E
authors.initials: E
authors.lastname: Ohuma
authors.forename: I
authors.initials: I
authors.lastname: Sarris
authors.forename: J
authors.initials: J
authors.lastname: Villar
authors.forename: A
authors.initials: A
authors.lastname: Conde-Agudelo
authors.forename: A T
authors.initials: AT
authors.lastname: Papageorghiou
mesh_terms: D000005:Abdomen / Q000000981:diagnostic imaging / Q000196:embryology; D000886:Anthropometry / Q000379:methods*; D003627:Data Interpretation, Statistical; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000196:embryology; D047109:Fetal Development; D057238:Growth Charts; D006257:Head / Q000000981:diagnostic imaging / Q000196:embryology; D006801:Humans; D010294:Parietal Bone / Q000000981:diagnostic imaging / Q000196:embryology; D011247:Pregnancy; D012044:Regression Analysis; D012107:Research Design / Q000592:standards*; D058028:Research Report; D016216:Ultrasonography, Prenatal / Q000379:methods* / Q000592:standards