title: Velamentous or marginal cord insertion and the risk of spontaneous preterm birth, prelabor rupture of the membranes, and anomalous cord length, a population-based study.
abstract: BACKGROUND
  Anomalous cord insertion is associated with increased risk of adverse maternal and perinatal outcome. Our aim was to study whether anomalous cord insertion is associated with prelabor rupture of membranes (PROM), preterm PROM (pPROM), long or short umbilical cord, and time trend of spontaneous preterm birth (SPTB) and anomalous cord insertion.
  
  
  METHODS
  A population-based register study using data from the Medical Birth Register of Norway including all singleton births (gestational age >16 weeks and <45 weeks) during 1999-2013 (n = 860 465) to calculate odds ratios (ORs) for PROM, pPROM, SPTB, and cord length (>95th or <5th centile) according to the cord insertion site by logistic regression with adjustment for possible confounders. We also assessed time trends of SPTB and anomalous cord insertion.
  
  
  RESULTS
  Velamentous insertion of the cord was associated with an increased risk of PROM (OR 1.6, 95% CI 1.5-1.7), pPROM (OR 2.7, 95% CI 2.4-3.0), SPTB (OR 2.0, 95% CI 1.9-2.2), and a short cord (OR 1.7, 95% CI 1.5-1.8). Marginal insertion was to a lesser extent associated with these complications. Occurrences of SPTB and anomalous insertion declined. The decline in SPTB persisted after including an interaction term between anomalous insertion and time.
  
  
  CONCLUSIONS
  Velamentous and, to a lesser extent, marginal cord insertions were associated with increased risk of PROM, pPROM, SPTB, and short cord. This suggests a common pathogenesis behind altered function of the membranes, cord, and placenta. The decline in SPTB could not be explained by the reduction in the occurrence of anomalous cord insertion.
authors.affiliation: Department of Obstetrics and Gynecology, Haukeland University Hospital, Bergen, Norway.
authors.forename: Cathrine
authors.identifier: http://orcid.org/0000-0002-4331-1250
authors.initials: C
authors.lastname: Ebbing
authors.affiliation: Department of Obstetrics and Gynecology, Haukeland University Hospital, Bergen, Norway.
authors.forename: Synnøve L
authors.identifier: http://orcid.org/0000-0003-3206-1943
authors.initials: SL
authors.lastname: Johnsen
authors.affiliation: Department of Obstetrics and Gynecology, Haukeland University Hospital, Bergen, Norway.|Department of Clinical Science, University of Bergen, Bergen, Norway.
authors.forename: Susanne
authors.initials: S
authors.lastname: Albrechtsen
authors.affiliation: Department of Clinical Science, University of Bergen, Bergen, Norway.
authors.forename: Ingvild D
authors.identifier: http://orcid.org/0000-0003-1752-7506
authors.initials: ID
authors.lastname: Sunde
authors.affiliation: Department of Clinical Science, University of Bergen, Bergen, Norway.
authors.forename: Christina
authors.identifier: http://orcid.org/0000-0001-5845-3369
authors.initials: C
authors.lastname: Vekseth
authors.affiliation: Department of Obstetrics and Gynecology, Haukeland University Hospital, Bergen, Norway.|Department of Clinical Science, University of Bergen, Bergen, Norway.
authors.forename: Svein
authors.identifier: http://orcid.org/0000-0002-5789-2922
authors.initials: S
authors.lastname: Rasmussen
mesh_terms: D000328:Adult; D005260:Female; D005322:Premature Rupture of Fetal Membranes / Q000453:epidemiology*; D006801:Humans; D008297:Male; D009664:Norway / Q000453:epidemiology; D016104:Oligohydramnios / Q000453:epidemiology; D006831:Polyhydramnios / Q000453:epidemiology; D011247:Pregnancy; D047928:Premature Birth / Q000453:epidemiology*; D012042:Registries; D012737:Sex Factors; D014470:Umbilical Cord / Q000002:abnormalities*; D055815:Young Adult
keywords: Delivery; high-risk pregnancy; placenta; pregnancy; preterm birth; rupture of membranes