title: Pregnancy and maternal chronic hepatitis B infection-Evidence of reproductive advantage?
abstract: As multiparas have high prevalence of chronic hepatitis B virus (HBV) infection, we examined here the relationship between the number of pregnancies with HBV infection.
  
  
  
  Retrospective cohort study examining the prevalence of HBV infection by actual gravidity and parity in 104 242 gravidae managed during 1997-2013.
  
  
  
  Infection rate increased from 8.5% to 10.6% for G1 to G≥6 and from 8.8% to 10.0% for P0 to P≥3 (P<.001). When stratified by parity, correlation with gravidity was maintained in the nulliparous gravidae. For the same gravidity, increasing parity was associated with higher rate of HBV infection for G2 and G3. Multiparas had higher HBV infection prevalence (all >10%) than nulliparas (<10%) for G2 to G≥4.
  
  
  
  Prior pregnancies, especially successful ones, are associated with increased HBV infection in an endemic population, which could have enhanced reproduction and in the process facilitated its transmission to the following generations.
authors.affiliation: Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China.
authors.forename: Terence T
authors.identifier: 0000-0001-7315-8747
authors.initials: TT
authors.lastname: Lao
authors.affiliation: Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China.
authors.forename: Daljit S
authors.initials: DS
authors.lastname: Sahota
mesh_terms: D000328:Adult; D005260:Female; D020073:Gravidity; D019694:Hepatitis B, Chronic / Q000453:epidemiology*; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D010298:Parity; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000453:epidemiology*; D015995:Prevalence; D012189:Retrospective Studies
keywords: abortion; fertility; gravidity; hepatitis B surface antigen; parity