title: The Nordic Obstetric Surveillance Study: a study of complete uterine rupture, abnormally invasive placenta, peripartum hysterectomy, and severe blood loss at delivery.
abstract: OBJECTIVE
  To assess the rates and characteristics of women with complete uterine rupture, abnormally invasive placenta, peripartum hysterectomy, and severe blood loss at delivery in the Nordic countries.
  
  
  METHODS
  Prospective, Nordic collaboration.
  
  
  METHODS
  The Nordic Obstetric Surveillance Study (NOSS) collected cases of severe obstetric complications in the Nordic countries from April 2009 to August 2012.
  
  
  METHODS
  Cases were reported by clinicians at the Nordic maternity units and retrieved from medical birth registers, hospital discharge registers, and transfusion databases by using International Classification of Diseases, 10th revision codes on diagnoses and the Nordic Medico-Statistical Committee Classification of Surgical Procedure codes.
  
  
  METHODS
  Rates of the studied complications and possible risk factors among parturients in the Nordic countries.
  
  
  RESULTS
  The studied complications were reported in 1019 instances among 605 362 deliveries during the study period. The reported rate of severe blood loss at delivery was 11.6/10 000 deliveries, complete uterine rupture was 5.6/10 000 deliveries, abnormally invasive placenta was 4.6/10 000 deliveries, and peripartum hysterectomy was 3.5/10 000 deliveries. Of the women, 25% had two or more complications. Women with complications were more often >35 years old, overweight, with a higher parity, and a history of cesarean delivery compared with the total population.
  
  
  CONCLUSIONS
  The studied obstetric complications are rare. Uniform definitions and valid reporting are essential for international comparisons. The main risk factors include previous cesarean section. The detailed information collected in the NOSS database provides a basis for epidemiologic studies, audits, and educational activities.
authors.affiliation: Department of Obstetrics, Rigshospitalet Copenhagen University Hospital/University of Copenhagen, Copenhagen, Denmark.
authors.forename: Lotte B
authors.initials: LB
authors.lastname: Colmorn
authors.affiliation: Fertility Clinic, Rigshospitalet Copenhagen University Hospital, Copenhagen, Denmark.
authors.forename: Kathrine B
authors.initials: KB
authors.lastname: Petersen
authors.affiliation: Department of Obstetrics and Gynecology, Helsinki University Central Hospital, Helsinki, Finland.
authors.forename: Maija
authors.initials: M
authors.lastname: Jakobsson
authors.affiliation: Clinitec, Karolinska Institute/Department of Gynecology and Obstetrics, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Pelle G
authors.initials: PG
authors.lastname: Lindqvist
authors.affiliation: Department of Global Public Health and Primary Care, University of Bergen/Medical Birth Register of Norway, Norwegian Institute of Public Health, Bergen, Norway.
authors.forename: Kari
authors.initials: K
authors.lastname: Klungsoyr
authors.affiliation: Epidemiology and Methodological Support Unit, Department of Evaluation and Analysis, National Board of Health and Welfare, Stockholm, Sweden.|Department of Obstetrics and Gynecology, Institution of Clinical Sciences, University of Lund, Lund, Sweden.
authors.forename: Karin
authors.initials: K
authors.lastname: Källen
authors.affiliation: Department of Obstetrics and Gynecology, Landspitali University Hospital, Reykjavik, Iceland.|Icelandic Medical Birth Register, Reykjavik, Iceland.
authors.forename: Ragnheidur I
authors.initials: RI
authors.lastname: Bjarnadottir
authors.affiliation: Department of Gynecology and Pediatrics, Helsinki University Central Hospital, Helsinki, Finland.|Department of Gynecology and Obstetrics, Hyvinkää Hospital, Helsinki and Uusimaa district, Finland.
authors.forename: Anna-Maija
authors.initials: AM
authors.lastname: Tapper
authors.affiliation: Haukeland Hospital, Bergen, Norway.
authors.forename: Per E
authors.initials: PE
authors.lastname: Børdahl
authors.affiliation: Epidemiology and Methodological Support Unit, Department of Evaluation and Analysis, National Board of Health and Welfare, Stockholm, Sweden.|Department of Obstetrics and Gynecology, Haukeland University Hospital/University of Bergen, Bergen, Norway.
authors.forename: Karin
authors.initials: K
authors.lastname: Gottvall
authors.affiliation: Department of Public Health Sciences, Karolinska Institute, Stockholm, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Thurn
authors.affiliation: Karlskrona County Hospital, Karlskrona, Sweden.|THL National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: Mika
authors.initials: M
authors.lastname: Gissler
authors.affiliation: Nordic School of Public Health, Gothenburg, Sweden.|Department of Obstetrics and Gynecology, Holbaek Hospital/University of Copenhagen, Holbaek, Denmark.
authors.forename: Lone
authors.initials: L
authors.lastname: Krebs
authors.affiliation: Department of Obstetrics, Rigshospitalet Copenhagen University Hospital/University of Copenhagen, Copenhagen, Denmark.
authors.forename: Jens
authors.initials: J
authors.lastname: Langhoff-Roos
mesh_terms: D000328:Adult; D002585:Cesarean Section / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007044:Hysterectomy / Q000706:statistics & numerical data*; D008423:Maternal Age; D050177:Overweight / Q000453:epidemiology; D010298:Parity; D010921:Placenta Accreta / Q000453:epidemiology*; D011159:Population Surveillance; D006473:Postpartum Hemorrhage / Q000453:epidemiology*; D011247:Pregnancy; D011446:Prospective Studies; D012307:Risk Factors; D012537:Scandinavian and Nordic Countries / Q000453:epidemiology; D014597:Uterine Rupture / Q000453:epidemiology*; D055815:Young Adult
keywords: Abnormally invasive placenta; multiple blood transfusions; peripartum hysterectomy; postpartum hemorrhage; uterine rupture