Objective To determine changes in hepatitis B virus (HBV) prevalence across three different time periods in pregnant women.

Methods This was a retrospective study of pregnant women attending four healthcare centres between January 1995 and May 2015. Data for serum hepatitis B surface antigen (HBsAg) and anti-HBs levels were collected from routine antenatal screening records. The 20-year study was divided into three periods: 1995–2001, 2002–2008 and 2009–2015. The results are presented by the women's age and gravidity as possible determinants of HBV infection.

Results 7605 pregnant women (56.0% primigravidae) (mean age 23.4±4.8 years) were tested for markers of HBV infection. 3010 pregnant women were screened between 1995 and 2001, 2995 between 2002 and 2008, and 1600 between 2009 and 2015. The overall prevalence of HBsAg and anti-HBs positivity in the 7605 pregnant women was 1.5% (n=114) and 11.5% (n=877), respectively. Regarding temporal change in the prevalence of HBV markers, HBsAg decreased significantly from 2.6% to 0.8% (p<0.01), while anti-HBs increased significantly from 9.5% to 17.5% (p<0.01), between the first and last study periods. Multigravidae and older women had higher HBsAg and anti-HBs positivity compared to primigravidae.

Conclusions The data suggest that the prevalence of HBsAg positivity is gradually decreasing among pregnant women, while the level of HBsAg antibody seropositivity is lower than expected. HBV carrier rate increases with increasing age and gravidity. In addition to the national HBV immunisation programme, the prevention of perinatal transmission should also be prioritised to decrease the HBV pool of infection.