Age Modifies the Association Between <scp>HBV DNA</scp> Levels and Liver Dysfunction Risk During Pregnancy

Hepatitis B virus (HBV) infection is a serious public health concern worldwide, especially during pregnancy due to the associated health risks for the mother and fetus. This study aimed to explore the relationship between alanine aminotransferase (ALT) levels, age and HBV DNA levels in pregnant women with chronic HBV infection. Our cohort study included 1743 pregnant women with HBV who gave birth from January 2021 to June 2024. Participants were divided into three groups based on HBV DNA levels (log IU/mL): low (≤ 3.3; n = 691), moderate (3.3-4.3; n = 398) and high (> 4.3; n = 654). We used modified Poisson regression models and linear trend tests to assess the relationships between HBV DNA levels and gestational minimally raised alanine aminotransferase (MRALT, 40-80 U/L) or raised alanine aminotransferase (RALT, > 80 U/L). Additionally, we evaluated the associations between MRALT/RALT and obstetric outcomes. In pregnant women of advanced maternal age (≥ 35 years), HBV DNA was independently linked to a higher incident RALT risk but not to MRALT risk. A gradient was evident between HBV DNA levels and RALT risk (p for trend < 0.001). Significant links between RALT and premature birth, as well as low birth weight, were found in both participants younger than 35 years and those older than 35 years, but without statistical significance in the latter group. Age significantly modified the association between elevated HBV DNA levels and RALT risk, highlighting the importance of age-stratified monitoring in pregnant women with chronic HBV infection. This highlights the importance of targeted management to prevent adverse outcomes.