title: Umbilical cord diameter percentile curves and their correlation to birth weight and placental pathology.
abstract: OBJECTIVE
  The aims of this study were to develop a nomogram of umbilical cord diameter (UCD) for pathologic examination of the placenta, to identify the umbilical cord components responsible for variations in UCD, and to examine the relationship between UCD and other placental pathologic features and perinatal outcome.
  
  
  METHODS
  We prospectively collected 497 umbilical cords between 18 and 41 weeks' gestation over a 1-year period. Fresh-tissue UCD were grouped according to gestational age and compared to sonographic and histological measurements. Associations between UCD percentile and placental pathologic findings or obstetrical outcomes were examined.
  
  
  RESULTS
  Mean UCD increased with gestational age until a plateau at 1.0 cm in the third trimester, a value that was 0.56 cm less than sonographic measurements prior to delivery and 0.17 cm greater than UCD measured histologically. Umbilical cord components varied with UCD percentile, with umbilical vessel area increased in thick cords (p < 0.001) and Wharton's jelly area reduced in thin cords (p = 0.002). Thin umbilical cords were associated with at least one pathologic histological placental finding (p = 0.02), low placental weight (p < 0.001), single umbilical artery (p = 0.02), marginal cord insertion (p = 0.01), and low infant birth weight (p < 0.001).
  
  
  CONCLUSIONS
  This study provides reference curves for post-delivery UCD from 18 to 41 weeks' gestation for use by perinatal pathologists. We show that increased UCD is a function of increased umbilical blood vessel volume and decreased UCD is a function of decreased Wharton's jelly volume. UCD shows a strong association with placental and infant birth weight.
authors.affiliation: Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario, Canada.
authors.forename: L K
authors.initials: LK
authors.lastname: Proctor
authors.forename: B
authors.initials: B
authors.lastname: Fitzgerald
authors.forename: W L
authors.initials: WL
authors.lastname: Whittle
authors.forename: N
authors.initials: N
authors.lastname: Mokhtari
authors.forename: E
authors.initials: E
authors.lastname: Lee
authors.forename: G
authors.initials: G
authors.lastname: Machin
authors.forename: J C P
authors.initials: JC
authors.lastname: Kingdom
authors.forename: S J
authors.initials: SJ
authors.lastname: Keating
mesh_terms: D001724:Birth Weight / Q000502:physiology*; D015331:Cohort Studies; D005260:Female; D005865:Gestational Age; D057238:Growth Charts; D006801:Humans; D007231:Infant, Newborn; D009929:Organ Size; D010922:Placenta Diseases / Q000209:etiology / Q000473:pathology*; D011247:Pregnancy; D011256:Pregnancy Outcome; D011379:Prognosis; D014470:Umbilical Cord / Q000033:anatomy & histology* / Q000254:growth & development / Q000473:pathology*; D059631:Wharton Jelly / Q000254:growth & development / Q000473:pathology