title: Association of chronic hepatitis B virus infection with preterm birth: our experience and meta-analysis.
abstract: OBJECTIVE
  To assess the association of chronic hepatitis B virus (HBV) infection with preterm birth (PTB).
  
  
  METHODS
  A cohort of 20,498 pregnant women (497 HBV carriers with 20,001 non-HBV controls) with normal alanine aminotransferase (ALT) levels was selected from the Obstetrics & Gynecology Hospital of Nantong University. The clinical parameters and PTB incidence were compared between HBV carriers and non-HBV subjects. For the meta-analysis, we searched the PubMed, Ovid and Cochrane Library databases for studies comparing PTB incidence between individuals with chronic HBV infection and non-HBV subjects.
  
  
  RESULTS
  HBV carriers were slightly older and had slightly higher ALT levels within normal limits. The body mass index, education and history of pregnancy between HBV carrier and non-HBV groups were comparable. PTB incidence was not associated with HBV carrier status [relative risk (RR) 0.98, 95% confidence interval (CI) 0.71-1.37] in our cohort. However, the meta-analysis involving eight published studies and our study revealed a significant association between chronic HBV infection and PTB incidence (pooled RR 1.26, 95% CI 1.19-1.33).
  
  
  CONCLUSIONS
  While maternal HBV carriers did not have a higher incidence of PTB in our cohort, the meta-analysis indicates that individuals with chronic HBV infection appeared to be at risk of PTB as a whole.
authors.affiliation: .
authors.forename: Ai-Min
authors.initials: AM
authors.lastname: Cui
authors.affiliation: .
authors.forename: Jian-Guo
authors.initials: JG
authors.lastname: Shao
authors.affiliation: .
authors.forename: Hai-Bo
authors.initials: HB
authors.lastname: Li
authors.affiliation: .
authors.forename: Yi
authors.initials: Y
authors.lastname: Shen
authors.affiliation: .
authors.forename: Zhi-Xian
authors.initials: ZX
authors.lastname: Chen
authors.affiliation: .
authors.forename: Sheng
authors.initials: S
authors.lastname: Zhang
authors.affiliation: .
authors.forename: Zhao-Lian
authors.initials: ZL
authors.lastname: Bian
authors.affiliation: .
authors.forename: Gang
authors.identifier: http://orcid.org/0000-0002-4363-2572
authors.initials: G
authors.lastname: Qin
authors.affiliation: .
authors.forename: Xiao-Yan
authors.initials: XY
authors.lastname: Cheng
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D002681:China / Q000453:epidemiology; D005260:Female; D019694:Hepatitis B, Chronic / Q000150:complications / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D011247:Pregnancy; D047928:Premature Birth / Q000453:epidemiology* / Q000821:virology; D011446:Prospective Studies; D055815:Young Adult
keywords: Cohort study; hepatitis B virus; meta-analysis; preterm birth