title: Prevalence of placenta previa among deliveries in Mainland China: A PRISMA-compliant systematic review and meta-analysis.
abstract: BACKGROUND
  Placenta previa is characterized by the abnormal placenta overlying the endocervical os, and it is known as one of the most feared adverse maternal and fetal-neonatal complications in obstetrics.
  
  
  OBJECTIVE
  We aimed to obtain overall and regional estimates of placenta previa prevalence among deliveries in Mainland China.
  
  
  METHODS
  The research was performed a systematic review, following the Meta-analysis of observational studies in epidemiology (MOOSE) guidelines for systematic reviews of observational studies, and the preferred reporting items for systematic reviews and meta-analysis (PRISMA) statement for reporting systematic reviews and meta-analysis. Electronic databases were searched and included hospital-based studies that reported placenta previa prevalence in Mainland China. Random-effects meta-analyses were used to pool prevalence estimates of placenta previa. Meta-regression analyses were performed to explore sources of heterogeneity across the included studies. For exploring the geographical distributions of placenta previa, the ArcGIS software (Esri) was used to construct the map of prevalence.
  
  
  RESULTS
  A total of 80 articles and 86 datasets (including 1,298,548 subjects and 14,199 placenta previa cases) from 1965 through 2015 were included. The pooled overall prevalence of placenta previa among deliveries was 1.24% (95% confidence interval [CI], 1.12-1.36) in Mainland China during 1965 to 2015. And, the trend in the prevalence of placenta previa was steady. The occurrence rate of placenta previa in the region groups Northeast, North, Northwest, Central China, East, South, and Southwest was 1.20%, 1.01%, 1.10%, 1.15%, 0.93%, 1.42%, and 2.01%, respectively. The prevalence map based on a geographic information system showed an unequal geographic distribution.
  
  
  CONCLUSIONS
  The results showed that placenta previa is currently a high-burden disease in Mainland China. This review would be useful for the design of placenta previa planning and implementation adequate health care systems and treatment programs in Mainland China.
authors.affiliation: Department of Obstetrics, South Medical University Affiliated Maternal & Child Health Hospital of Foshan, Foshan, Guangdong School of Integrated Traditional and Western Medicine, Anhui University of Chinese Medicine, Hefei, Anhui Department of Epidemiology and Biostatistics, School of Public Health, Anhui Medical University, Hefei, Anhui The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
authors.forename: Dazhi
authors.initials: D
authors.lastname: Fan
authors.forename: Song
authors.initials: S
authors.lastname: Wu
authors.forename: Wen
authors.initials: W
authors.lastname: Wang
authors.forename: Lihong
authors.initials: L
authors.lastname: Xin
authors.forename: Guo
authors.initials: G
authors.lastname: Tian
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.forename: Jinping
authors.initials: J
authors.lastname: Feng
authors.forename: Xiaoling
authors.initials: X
authors.lastname: Guo
authors.forename: Zhengping
authors.initials: Z
authors.lastname: Liu
mesh_terms: D002681:China / Q000453:epidemiology; D036861:Delivery, Obstetric / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D010923:Placenta Previa / Q000453:epidemiology*; D011247:Pregnancy; D015995:Prevalence