At the age of seven months, we extract venous blood of these children, separate the serums and collect the PBMC. Then, the serums are applied to test HBsAg, AntiHBs and HBVDNA which we adopt to analyse HLA classⅠand class Ⅱ gene polymorphism. meanwhile, detect HBVDNA loads of pregnant women with HBsAg/HBeAg positive and HBV DNA > 106 copies/ml in 32 weeks，36 weeks of gestation and before delivery.