title: The risk of placental abruption and placenta previa in pregnant women with chronic hepatitis B viral infection: a systematic review and meta-analysis.
abstract: BACKGROUND
  Several epidemiological studies have found a positive association between chronic hepatitis B virus (CHB) infection and the risk of placental abruption and placenta previa, but various studies have reported conflicting findings. The objective was to systematically review the literature to determine a possible association between CHB infection and these two placental complications.
  
  
  METHODS
  We conducted a computerized search in electronic database through March 1, 2014, supplemented with a manual search of reference lists, to identify original published research on placental abruption and placenta previa rates in women with CHB infection. Data were independently extracted, and relative risks were calculated. The meta-analysis was performed using Stata version 10.0 software.
  
  
  RESULTS
  Five studies involving 9088 placenta previa cases were identified. No significant association between CHB infection and placenta previa was identified (OR = 0.98, 95% CI = 0.60-1.62). Five studies involving 15571 placental abruption cases were identified. No significant association between CHB infection and placental abruption was identified (OR = 1.42, 95% CI, 0.93-2.15).
  
  
  CONCLUSIONS
  The immune response against the virus represents a key factor in determining infection outcomes. No observation of significant increased risk of the placental complications could be partially explained by the complex immune response during CHB infection.
  
  
  CONCLUSIONS
  Our meta-analysis found no evidence of significant associations between CHB infection and increased risk of placental abruption as well as placenta previa. Further well-designed studies were warranted to assess any potential association between CHB infection and increased risk of placental abruption as well as placenta previa.
authors.affiliation: Division of Obstetrics and Gynecology, Nanfang Hospital, Southern Medical University, 1838 North Guangzhou Avenue, Guangzhou 510515, China; Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, University of Toronto, Toronto M5T 3H7, Canada.
authors.forename: Q T
authors.initials: QT
authors.lastname: Huang
authors.affiliation: Division of Obstetrics and Gynecology, Nanfang Hospital, Southern Medical University, 1838 North Guangzhou Avenue, Guangzhou 510515, China.
authors.forename: J H
authors.initials: JH
authors.lastname: Chen
authors.affiliation: Division of Obstetrics and Gynecology, Nanfang Hospital, Southern Medical University, 1838 North Guangzhou Avenue, Guangzhou 510515, China. Electronic address: zhongm1960@163.com.
authors.forename: M
authors.initials: M
authors.lastname: Zhong
authors.affiliation: Division of Obstetrics and Gynecology, Nanfang Hospital, Southern Medical University, 1838 North Guangzhou Avenue, Guangzhou 510515, China.
authors.forename: Y Y
authors.initials: YY
authors.lastname: Xu
authors.affiliation: Division of Obstetrics and Gynecology, Nanfang Hospital, Southern Medical University, 1838 North Guangzhou Avenue, Guangzhou 510515, China.
authors.forename: C X
authors.initials: CX
authors.lastname: Cai
authors.affiliation: Division of Obstetrics and Gynecology, Nanfang Hospital, Southern Medical University, 1838 North Guangzhou Avenue, Guangzhou 510515, China.
authors.forename: S S
authors.initials: SS
authors.lastname: Wei
authors.affiliation: Division of Obstetrics and Gynecology, Nanfang Hospital, Southern Medical University, 1838 North Guangzhou Avenue, Guangzhou 510515, China.
authors.forename: L L
authors.initials: LL
authors.lastname: Hang
authors.affiliation: Cancer Research Center, Shantou University Medical College, Shantou 515041, China.
authors.forename: Q
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Division of Obstetrics and Gynecology, Nanfang Hospital, Southern Medical University, 1838 North Guangzhou Avenue, Guangzhou 510515, China.
authors.forename: Y H
authors.initials: YH
authors.lastname: Yu
mesh_terms: D000037:Abruptio Placentae / Q000821:virology*; D005260:Female; D019694:Hepatitis B, Chronic / Q000150:complications*; D006801:Humans; D010923:Placenta Previa / Q000821:virology*; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000821:virology*
keywords: HBV; Placenta previa; Placental abruption; Placental complications