title: Cord coiling, umbilical cord insertion and placental shape in an unselected cohort delivering at term: relationship with common obstetric outcomes.
abstract: BACKGROUND
  The position of the placental cord insertion, its shape and cord coiling are thought to be associated with perinatal outcome. This study derives indices describing the relationship of cord insertion to the placental centre, the shape of the placenta and cord coiling in placentas from unselected term pregnancies. Further, we investigate these indices in pregnancies affected by pre-eclampsia (PET), pregnancy induced hypertension (PIH), gestational diabetes mellitus (GDM) and delivery of a small for gestational age (SGA) baby.
  
  
  METHODS
  Eight hundred and sixty one unselected women with singleton pregnancy delivering at 37-42 weeks were prospectively recruited to this study. Placental axes and their relationship with the cord insertion were measured using digital photography and proprietary software. From these, the cord centrality (distance of umbilical cord insertion from the centre) and placental eccentricity (deviation of the placental shape from circular) were derived. The cord coiling index (number of coils in the cord divided by the length of cord in cm) was also calculated from manual measurements.
  
  
  RESULTS
  The mean value of cord centrality index was 0.36 (SD = 0.21) and of placental eccentricity 0.49 (SD = 0.17). Left direction of umbilical cord coiling was more common than right (79% vs 16.4%) The mean cord coiling index was 0.20 (SD = 0.09) coils/cm. The indices were constant between 37 and 42 weeks and were no different in the non-affected population compared to women with pre-eclampsia (n = 17), PIH, (n = 27), GDM (n = 38) or delivery of an SGA baby (n = 54).
  
  
  CONCLUSIONS
  The cord centrality index that we derive suggests that the cord insertion is most commonly 'off centre', and eccentricity index that the placental shape is elliptical. Therefore, contrary to widely held belief, the cord does not normally insert centrally nor is the placenta normally round in shape. There is a preponderance of left sided coiling. There was no difference for any of the indices between the non-affected pregnancies and pregnancies affected by pre-eclampsia, PIH, GDM and SGA.
authors.affiliation: Division of Fetal-Maternal Medicine, Rosie Maternity-Addenbrookes Hospital, Cambridge Universiy Hospitals NHS Foundation Trust, Hills Road, Cambridge CB2 2QQ, UK.
authors.forename: S
authors.initials: S
authors.lastname: Pathak
authors.forename: E
authors.initials: E
authors.lastname: Hook
authors.forename: G
authors.initials: G
authors.lastname: Hackett
authors.forename: E
authors.initials: E
authors.lastname: Murdoch
authors.forename: N J
authors.initials: NJ
authors.lastname: Sebire
authors.forename: F
authors.initials: F
authors.lastname: Jessop
authors.forename: C
authors.initials: C
authors.lastname: Lees
mesh_terms: D000328:Adult; D000465:Algorithms; D002823:Chorion; D015331:Cohort Studies; D016640:Diabetes, Gestational; D005260:Female; D006801:Humans; D046110:Hypertension, Pregnancy-Induced; D007091:Image Processing, Computer-Assisted; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D009929:Organ Size; D010781:Photography; D010920:Placenta / Q000033:anatomy & histology* / Q000098:blood supply*; D011225:Pre-Eclampsia; D011247:Pregnancy; D011248:Pregnancy Complications; D011256:Pregnancy Outcome; D047929:Term Birth; D014470:Umbilical Cord / Q000033:anatomy & histology*; D055815:Young Adult