title: Identifying regional variation in the prevalence of postpartum haemorrhage: a systematic review and meta-analysis.
abstract: OBJECTIVE
  To provide regional estimates of the prevalence of maternal haemorrhage and explore the effect of methodological differences between studies on any observed regional variation.
  
  
  METHODS
  We conducted a systematic review of the prevalence of maternal haemorrhage, defined as blood loss greater than or equal to 1) 500 ml or 2) 1000 ml in the antepartum, intrapartum or postpartum period. We obtained regional estimates of the prevalence of maternal and severe maternal haemorrhage by conducting meta-analyses and used meta-regression to explore potential sources of between-study heterogeneity.
  
  
  RESULTS
  No studies reported the prevalence of antepartum haemorrhage (APH) according to our definitions. The prevalence of postpartum haemorrhage (PPH) (blood loss ≥500 ml) ranged from 7.2% in Oceania to 25.7% in Africa. The prevalence of severe PPH (blood loss ≥1000 ml) was highest in Africa at 5.1% and lowest in Asia at 1.9%. There was strong evidence of between-study heterogeneity in the prevalence of PPH and severe PPH in most regions. Meta-regression analyses suggested that region and method of measurement of blood loss influenced prevalence estimates for both PPH and severe PPH. The regional patterns changed after adjusting for the other predictors of PPH indicating that, compared with European women, Asian women have a lower prevalence of PPH.
  
  
  CONCLUSIONS
  We found evidence that Asian women have a very low prevalence of PPH compared with women in Europe. However, more reliable estimates will only be obtained with the standardisation of the measurement of PPH so that the data from different regions are comparable.
authors: London School of Hygiene and Tropical Medicine, London, United Kingdom. clara.calvert@lshtm.ac.uk
authors: Clara
authors: C
authors: Calvert
authors: Sara L
authors: SL
authors: Thomas
authors: Carine
authors: C
authors: Ronsmans
authors: Karen S
authors: KS
authors: Wagner
authors: Alma J
authors: AJ
authors: Adler
authors: Veronique
authors: V
authors: Filippi
mesh_terms: D006801:Humans; D038622:Internationality; D006473:Postpartum Hemorrhage / Q000453:epidemiology*; D015995:Prevalence