Mother-to-child transmission (MTCT) is the most common route of hepatitis B virus (HBV) infection. After given standard immunoprophylaxis, MTCT still occurred in some infants born to a HBsAg positive mothers with high HBV DNA load. The main purpose of this study is evaluating the efficacy of methods used in blocking MTCT of HBV in infants born to a HBsAg positive mothers with high serum HBV DNA loads.