title: Prevalence of placenta praevia by world region: a systematic review and meta-analysis.
abstract: OBJECTIVE
  (i) To estimate the prevalence burden of placenta praevia in each world region, and (ii) to investigate potential sources of heterogeneity.
  
  
  METHODS
  Systematic review of the literature and random-effects meta-analysis. Potential sources of heterogeneity were investigated using meta-regression.
  
  
  RESULTS
  The overall prevalence of placenta praevia was 5.2 per 1000 pregnancies (95% CI: 4.5-5.9). However, there was evidence of regional variation (P = 0.0001); prevalence was highest among Asian studies (12.2 per 1000 pregnancies; 95% CI: 9.5-15.2) and lower among studies from Europe (3.6 per 1000 pregnancies; 95% CI: 2.8-4.6), North America (2.9 per 1000 pregnancies; 95% CI: 2.3-3.5) and Sub-Saharan Africa (2.7 per 1000 pregnancies; 95% CI: 0.3-11.0). The prevalence of major placenta praevia was 4.3 per 1000 pregnancies (95% CI: 3.3-5.4).
  
  
  CONCLUSIONS
  The prevalence of placenta praevia is low at around 5 per 1000 pregnancies. There is some evidence suggestive of regional variation in its prevalence, but it is not possible to determine from existing data whether this is due to true ethnic differences or other unknown factor(s).
authors.affiliation: London School of Hygiene & Tropical Medicine, London, UK. jenny.cresswell@lshtm.ac.uk
authors.forename: Jenny A
authors.initials: JA
authors.lastname: Cresswell
authors.forename: Carine
authors.initials: C
authors.lastname: Ronsmans
authors.forename: Clara
authors.initials: C
authors.lastname: Calvert
authors.forename: Véronique
authors.initials: V
authors.lastname: Filippi
mesh_terms: D017954:Africa South of the Sahara / Q000453:epidemiology; D001208:Asia / Q000453:epidemiology; D005060:Europe / Q000453:epidemiology; D005260:Female; D006801:Humans; D008429:Maternal Welfare / Q000706:statistics & numerical data*; D009656:North America / Q000453:epidemiology; D010923:Placenta Previa / Q000453:epidemiology*; D006473:Postpartum Hemorrhage / Q000453:epidemiology / Q000209:etiology; D011247:Pregnancy; D015995:Prevalence; D012044:Regression Analysis; D060728:Reproductive Health / Q000706:statistics & numerical data*