title: Abnormally invasive placenta-prevalence, risk factors and antenatal suspicion: results from a large population-based pregnancy cohort study in the Nordic countries.
abstract: OBJECTIVE
  The objective was to investigate prevalence, estimate risk factors, and antenatal suspicion of abnormally invasive placenta (AIP) associated with laparotomy in women in the Nordic countries.
  
  
  METHODS
  Population-based cohort study.
  
  
  METHODS
  A 3-year Nordic collaboration among obstetricians to identify and report on uterine rupture, peripartum hysterectomy, excessive blood loss, and AIP from 2009 to 2012 The Nordic Obstetric Surveillance Study (NOSS).
  
  
  METHODS
  In the NOSS study, clinicians reported AIP cases from maternity wards and the data were validated against National health registries.
  
  
  METHODS
  Prevalence, risk factors, antenatal suspicion, birth complications, and risk estimations using aggregated national data.
  
  
  RESULTS
  A total of 205 cases of AIP in association with laparotomy were identified, representing 3.4 per 10 000 deliveries. The single most important risk factor, which was reported in 49% of all cases of AIP, was placenta praevia. The risk of AIP increased seven-fold after one prior caesarean section (CS) to 56-fold after three or more CS. Prior postpartum haemorrhage was associated with six-fold increased risk of AIP (95% confidence interval 3.7-10.9). Approximately 70% of all cases were not diagnosed antepartum. Of these, 39% had prior CS and 33% had placenta praevia.
  
  
  CONCLUSIONS
  Our findings indicate that a lower CS rate in the population may be the most effective way to lower the incidence of AIP. Focused ultrasound assessment of women at high risk will likely strengthen antenatal suspicion. Prior PPH is a novel risk factor associated with an increased prevalence of AIP.
  
  
  CONCLUSIONS
  An ultrasound assessment in women with placenta praevia or prior CS may double the awareness for AIP.
authors.affiliation: Department of Obstetrics and Gynaecology, Blekinge Hospital, Karlskrona, Sweden.
authors.forename: L
authors.initials: L
authors.lastname: Thurn
authors.affiliation: Department of Obstetrics and Gynaecology, Clintec, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: P G
authors.initials: PG
authors.lastname: Lindqvist
authors.affiliation: Department of Obstetrics and Gynaecology, University Hospital, Helsinki, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Jakobsson
authors.affiliation: Department of Obstetrics, Rigshospitalet, Copenhagen, Denmark.
authors.forename: L B
authors.initials: LB
authors.lastname: Colmorn
authors.affiliation: Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway.|Medical Birth Registry of Norway, Norwegian Institute of Public Health, Bergen, Norway.
authors.forename: K
authors.initials: K
authors.lastname: Klungsoyr
authors.affiliation: Department of Obstetrics and Gynaecology, Landspitali University Hospital, Reykjavik, Iceland.
authors.forename: R I
authors.initials: RI
authors.lastname: Bjarnadóttir
authors.affiliation: Department of Gynaecology and Paediatrics, University Hospital, Helsinki, Finland.
authors.forename: A M
authors.initials: AM
authors.lastname: Tapper
authors.affiliation: Department of Obstetrics and Gynaecology, Haukeland University Hospital, University of Bergen, Bergen, Norway.
authors.forename: P E
authors.initials: PE
authors.lastname: Børdahl
authors.affiliation: Department of Evaluation and Analysis, Epidemiology and Methodological support unit, National Board of Health and Welfare, Stockholm, Sweden.|Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Gottvall
authors.affiliation: Fertility Clinic, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.
authors.forename: K B
authors.initials: KB
authors.lastname: Petersen
authors.affiliation: Department of Obstetrics and Gynaecology, Holbaek Hospital, Holbaek and University of Copenhagen, Copenhagen, Denmark.
authors.forename: L
authors.initials: L
authors.lastname: Krebs
authors.affiliation: THL National Institute for Health and Welfare, Helsinki, Finland.|Nordic School of Public Health, Gothenburg, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Gissler
authors.affiliation: Department of Obstetrics, Rigshospitalet, Copenhagen, Denmark.
authors.forename: J
authors.initials: J
authors.lastname: Langhoff-Roos
authors.affiliation: Department of Evaluation and Analysis, Epidemiology and Methodological support unit, National Board of Health and Welfare, Stockholm, Sweden.|Department of Reproduction Epidemiology, Tornblad Institute, Institution of Clinical Sciences, Lund University, Lund, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Källen
mesh_terms: D000328:Adult; D002585:Cesarean Section / Q000706:statistics & numerical data*; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D007044:Hysterectomy / Q000706:statistics & numerical data*; D007055:Iceland / Q000453:epidemiology; D015994:Incidence; D009664:Norway / Q000453:epidemiology; D058725:Peripartum Period; D010921:Placenta Accreta / Q000000981:diagnostic imaging / Q000453:epidemiology*; D006473:Postpartum Hemorrhage / Q000453:epidemiology*; D011247:Pregnancy; D015995:Prevalence; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology; D014463:Ultrasonography; D016216:Ultrasonography, Prenatal; D014597:Uterine Rupture / Q000453:epidemiology*; D055815:Young Adult
keywords: Incidence; placenta accreta; prenatal diagnosis; risk factors