Abstract: Objective To explore the prevalence and S region characteristics of isolated hepatitis B virus (HBV) among pregnant women with overt and occult HBV infection.Methods A cross-sectional study was conducted among 156 pregnant women recruited continuously from June 1,2014 to June 31,2014 in a hospital in Anqing city of Anhui province.Blood samples were collected and detected for HBV surface antigen(HBsAg)by using enzyme linked immunosorbent assay(ELISA)and electrochemiluminescence immunoassay.Real-time PCR was applied to quantify HBV DNA.Nested polymerase chain reaction and sequencing of HBV S gene were also performed for all samples.Phylogenetic analysis was performed using MEGA 6.0 software.Results The prevalence HBV infection was 17.95%(28/156)and the proportions of overt and occult infection were 10.3%(16/156)and 8.6%(12/140),respectively,among the pregnant women.S gene sequences were obtained for 13 HBV strains isolated from 7 overt and 6 occult HBV infections.All the isolated HBV strains were serotype adw2 of genotype B,except for one serotype ayw1 isolated from one occult infection.Conclusion The prevalence of overt and occult HBV infection is high among pregnant women in Anqing city of Anhui province.