title: The umbilical coiling index in normal pregnancy.
abstract: OBJECTIVE
  To provide reference values for the umbilical coiling index in uncomplicated pregnancy.
  
  
  METHODS
  Umbilical cords were collected from livebom singleton infants born after uncomplicated pregnancies. The umbilical coiling index (UCI) was calculated as the number of coils divided by the cord length in centimeters. The mean value (SD) for the UCI was calculated, and possible correlations of the UCI with maternal age, parity, gestational age at delivery, mode of delivery, sex and birth weight of the infant were examined.
  
  
  RESULTS
  A total of 122 umbilical cords were included. The frequency distribution of the UCI was skewed to the right. The mean (SD) UCI was 0.17 (0.009) coils/cm. There were no significant correlations of the UCI with maternal age, parity, gestational age at delivery, mode of delivery, sex or birth weight of the infant.
  
  
  CONCLUSIONS
  This is the first study to determine the UCI in a group exclusively consisting of uncomplicated pregnancies. The mean value that we found for the UCI may serve as the standard reference, allowing proper interpretation of umbilical coiling in complicated pregnancy.
authors.affiliation: Department of Obstetrics, University Medical Center, Utrecht, The Netherlands.
authors.forename: C C
authors.initials: CC
authors.lastname: van Diik
authors.forename: A
authors.initials: A
authors.lastname: Franx
authors.forename: M W M
authors.initials: MW
authors.lastname: de Laat
authors.forename: H W
authors.initials: HW
authors.lastname: Bruinse
authors.forename: G H A
authors.initials: GH
authors.lastname: Visser
authors.forename: P G J
authors.initials: PG
authors.lastname: Nikkels
mesh_terms: D000328:Adult; D001837:Body Weights and Measures / Q000379:methods; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D011247:Pregnancy; D011248:Pregnancy Complications / Q000503:physiopathology; D012016:Reference Values; D014470:Umbilical Cord / Q000033:anatomy & histology* / Q000196:embryology