Viral factors for HBV mother-to-child transmission.

Chronic hepatitis B virus (HBV) remains a leading cause of cirrhosis and hepatocellular carcinoma worldwide. Because chronic hepatitis B infection is rarely eradicated, preventing mother-to-child transmission (MTCT) is the most effective strategy to eliminate HBV globally. Although immunoprophylaxis strategy is widely available and effective for infants born to mothers with chronic hepatitis B infection, postnatal immunoprophylaxis fails in approximately 5-10 % of infants, and this failure rate goes up to 30 % in infants born to highly viremic mothers. Mothers with HBV DNA levels above 200,000 IU/mL should be managed aggressively with antiviral therapy because viral load is the strongest independent risk factor for immunoprophylaxis failure. Emerging data suggest that initiation of antiviral therapy in late pregnancy in highly viremic mothers can prevent immunoprophylaxis failure in their infants. Reducing viral load to target levels below 200,000 IU/mL at delivery is a practical approach to control MTCT. This review focuses on viral factors in mothers associated with MTCT.