Seroepidemiological Characteristics and Influencing Factors of Hepatitis B Virus Infection Among Pregnant Women in Nanning City, China (2024–2025): A Cross-Sectional Study

Hepatitis B virus (HBV) infection remains a major public health concern among pregnant women, with regional disparities in epidemic characteristics that hinder precise prevention of mother-to-child transmission (MTCT). This study aimed to characterize the seroepidemiological profiles of HBV infection and identify its associated influencing factors among pregnant women in Nanning City, providing evidence-based insights for optimizing targeted interventions to block HBV MTCT. A stratified cluster random sampling strategy was adopted to recruit pregnant women receiving routine antenatal care at designated medical institutions across Nanning between October 2024 and May 2025. Standardized face-to-face questionnaires were administered to collect demographic, behavioral, and disease-related data. Venous blood samples were collected for quantitative detection of five serological HBV markers via chemiluminescence immunoassay. The Kruskal–Wallis test was used to compare the geometric mean concentration (GMC) of hepatitis B surface antibody (HBsAb), while the chi-square test was applied to analyze intergroup differences in the seropositivity rates of the five HBV markers. Multivariate unconditional logistic regression models were constructed to explore factors independently associated with seropositivity of hepatitis B surface antigen (HBsAg), HBsAb, and hepatitis B core antibody (HBcAb). A total of 1,935 eligible pregnant women were enrolled. The overall seropositivity rates of HBsAg, HBsAb, hepatitis B e-antigen (HBeAg), hepatitis e-antibody (HBeAb), and HBcAb were 6.98%, 59.48%, 1.50%, 15.50%, and 33.02%, respectively. Seropositivity of HBsAg, HBsAb, HBeAb, and HBcAb exhibited an age-dependent ascending trend, with the lowest rates observed in the 14–19 age group and peak rates in the 40–49 age group. Rural residents presented significantly higher HBsAg and HBeAb seropositivity but lower HBsAb seropositivity compared with urban counterparts. Participants with unknown or no prior HBV vaccination history showed markedly higher seropositivity of HBsAg, HBeAg, HBeAb, and HBcAb, alongside reduced HBsAb positivity, relative to those vaccinated within the past 5 years or ≥5 years prior (all P < 0.001). Furthermore, individuals vaccinated ≥5 years ago demonstrated higher HBV marker seropositivity and lower HBsAb positivity than those vaccinated within 5 years (all P < 0.001). Multivariate logistic regression revealed that advanced maternal age, rural residency, comorbid chronic underlying diseases, and close contact with HBV carriers/patients were independent risk factors for HBsAg seropositivity, whereas prior HBV vaccination exerted a protective effect. Advanced age, higher educational attainment, and HBV vaccination history independently predicted higher odds of HBsAb positivity; rural residency, chronic comorbidities, and non-medical occupational status were risk factors for insufficient HBsAb seroconversion. For HBcAb seropositivity, advanced age, chronic underlying diseases, and exposure to HBV-infected individuals were independent risk factors, while higher education and vaccination history served as protective factors. HBV prevalence among pregnant women in Nanning exceeds the national average, accompanied by prominent urban–rural disparities. Advanced maternal age and the presence of chronic comorbidities increase HBV infection vulnerability, while vaccination coverage among childbearing-age women remains suboptimal with progressive attenuation of protective antibody titers over time. We recommend targeted booster HBV vaccination for childbearing-age women with insufficient HBsAb levels to curb incident HBV infections and mitigate the risk of vertical transmission.