title: Incidence and risk factors for placenta accreta/increta/percreta in the UK: a national case-control study.
abstract: BACKGROUND
  Placenta accreta/increta/percreta is associated with major pregnancy complications and is thought to be becoming more common. The aims of this study were to estimate the incidence of placenta accreta/increta/percreta in the UK and to investigate and quantify the associated risk factors.
  
  
  METHODS
  A national case-control study using the UK Obstetric Surveillance System was undertaken, including 134 women diagnosed with placenta accreta/increta/percreta between May 2010 and April 2011 and 256 control women.
  
  
  RESULTS
  The estimated incidence of placenta accreta/increta/percreta was 1.7 per 10,000 maternities overall; 577 per 10,000 in women with both a previous caesarean delivery and placenta praevia. Women who had a previous caesarean delivery (adjusted odds ratio (aOR) 14.41, 95%CI 5.63-36.85), other previous uterine surgery (aOR 3.40, 95%CI 1.30-8.91), an IVF pregnancy (aOR 32.13, 95%CI 2.03-509.23) and placenta praevia diagnosed antepartum (aOR 65.02, 95%CI 16.58-254.96) had raised odds of having placenta accreta/increta/percreta. There was also a raised odds of placenta accreta/increta/percreta associated with older maternal age in women without a previous caesarean delivery (aOR 1.30, 95%CI 1.13-1.50 for every one year increase in age).
  
  
  CONCLUSIONS
  Women with both a prior caesarean delivery and placenta praevia have a high incidence of placenta accreta/increta/percreta. There is a need to maintain a high index of suspicion of abnormal placental invasion in such women and preparations for delivery should be made accordingly.
authors.affiliation: National Perinatal Epidemiology Unit, University of Oxford, Oxford, United Kingdom. kate.fitzpatrick@npeu.ox.ac.uk
authors.forename: Kathryn E
authors.initials: KE
authors.lastname: Fitzpatrick
authors.forename: Susan
authors.initials: S
authors.lastname: Sellers
authors.forename: Patsy
authors.initials: P
authors.lastname: Spark
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Kurinczuk
authors.forename: Peter
authors.initials: P
authors.lastname: Brocklehurst
authors.forename: Marian
authors.initials: M
authors.lastname: Knight
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D002585:Cesarean Section / Q000009:adverse effects; D062665:Epidemiological Monitoring; D005260:Female; D006801:Humans; D015994:Incidence; D008423:Maternal Age; D016017:Odds Ratio; D010921:Placenta Accreta / Q000453:epidemiology* / Q000209:etiology; D010923:Placenta Previa / Q000453:epidemiology* / Q000209:etiology; D011247:Pregnancy; D012307:Risk Factors; D006113:United Kingdom / Q000453:epidemiology