Some domestic studies have shown that in vertical transmission of hepatitis B virus, paternal-infant transmission of hepatitis B virus is more likely than maternal-infant transmission and is more likely to result in lifelong carriage. In men with hepatitis B, hepatitis B virus DNA can be detected in their sperm, and as the sperm enters the egg cell, the hepatitis B virus proliferates during the formation of the embryo, even though the mother does not have hepatitis, making the offspring hepatitis B patients or carriers, thus, this mode of transmission of hepatitis B virus is called paternal-infant transmission. The chances of this mode of transmission are relatively small. When the father is double-positive for surface antigen and e antigen, the chance of infection in his offspring can be more than 80%; when the father is positive for e antibody, the chance of infection in his offspring is about 20%. In addition, even if there is no hepatitis B virus infection at the time of fertilization, as long as the couple lives together during pregnancy, the pregnant woman is still not free from the risk of being infected by her husband’s hepatitis B virus. This is because close contact in daily life and sexual intercourse during pregnancy may cause the pregnant woman to be infected with the hepatitis B virus, which in turn may infect the offspring through the father-mother-infant method, which is actually a form of indirect father-to-child transmission.