title: Reporting errors, incidence and risk factors for postpartum haemorrhage and progression to severe PPH: a prospective observational study.
abstract: OBJECTIVE
  To quantify reporting errors, measure incidence of postpartum haemorrhage (PPH) and define risk factors for PPH (≥500 ml) and progression to severe PPH (≥1500 ml).
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  Two UK maternity services.
  
  
  METHODS
  Women giving birth between 1 August 2008 and 31 July 2009 (n = 10 213).
  
  
  METHODS
  Weighted sampling with sequential adjustment by multivariate analysis.
  
  
  METHODS
  Incidence and risk factors for PPH and progression to severe PPH.
  
  
  RESULTS
  Errors in transcribing blood volume were frequent (14%) with evidence of threshold preference and avoidance. The incidences of PPH ≥500, ≥1500 and ≥2500 ml were 33.7% (95% CI 31.2-36.2), 3.9% (95% CI 3.3-4.6) and 0.8% (95% CI 0.6-1.0). New independent risk factors predicting PPH ≥ 500 ml included Black African ethnicity (adjusted odds ratio [aOR] 1.77, 95% CI 1.31-2.39) and assisted conception (aOR 2.93, 95% CI 1.30-6.59). Modelling demonstrated how prepregnancy- and pregnancy-acquired factors may be mediated through intrapartum events, including caesarean section, elective (aOR 24.4, 95% CI 5.53-108.00) or emergency (aOR 40.5, 95% CI 16.30-101.00), and retained placenta (aOR 21.3, 95% CI 8.31-54.7). New risk factors were identified for progression to severe PPH, including index of multiple deprivation (education, skills and training) (aOR 1.75, 95% CI 1.11-2.74), multiparity without caesarean section (aOR 1.65, 95% CI 1.20-2.28) and administration of steroids for fetal reasons (aOR 2.00, 95% CI 1.24-3.22).
  
  
  CONCLUSIONS
  Sequential, interacting, traditional and new risk factors explain the highest rates of PPH and severe PPH reported to date.
authors: Division of Women's Health, Women's Health Academic Centre, King's College London and King's Health Partners, St Thomas' Hospital Campus, London, UK.
authors: A
authors: A
authors: Briley
authors: P T
authors: PT
authors: Seed
authors: G
authors: G
authors: Tydeman
authors: H
authors: H
authors: Ballard
authors: M
authors: M
authors: Waterstone
authors: J
authors: J
authors: Sandall
authors: L
authors: L
authors: Poston
authors: R M
authors: RM
authors: Tribe
authors: S
authors: S
authors: Bewley
mesh_terms: D018450:Disease Progression; D005260:Female; D006801:Humans; D015994:Incidence; D019300:Medical Errors / Q000706:statistics & numerical data*; D006473:Postpartum Hemorrhage / Q000453:epidemiology* / Q000209:etiology*; D011247:Pregnancy; D011446:Prospective Studies; D012307:Risk Factors; D012308:Risk Management / Q000706:statistics & numerical data*; D012720:Severity of Illness Index
keywords: Blood loss; observational study; pregnancy; progression; risk factors; severe adverse maternal morbidity