Identifying Regional Variation in the Prevalence of Postpartum Haemorrhage: A Systematic Review and Meta-Analysis Calvert, Clara ; Thomas, Sara L. ; Ronsmans, Carine ; Wagner, Karen S. ; Adler, Alma J. ; Filippi, Veronique Abstract Publication: PLoS ONE Pub Date: July 2012 DOI: 10.1371/journal.pone.0041114 Bibcode: 2012PLoSO...741114C