Mother-to-child transmission is the process by which a mother who is surface antigen positive for hepatitis B, especially a mother who is double positive for surface antigen and e antigen (commonly known as a major triplet), can transmit the hepatitis B virus to her infant, causing the infant to become infected with HBV. Mothers who are positive for both HBsAg and HBeAg will have approximately 80% of their children infected. Since the immune organs and functions of newborns are not yet mature, they often develop immune tolerance to the hepatitis B virus after infection, and not only carry the virus themselves for a long time and infect others, but also respond poorly to anti-hepatitis B virus medication, resulting in the gathering of many families with chronic hepatitis B patients. Therefore, it is an important measure to prevent hepatitis B virus infection in China to try to cut off the mother-to-child transmission route. The process of mother-to-child transmission can be divided into three stages: transmission through the placenta during pregnancy, transmission during labor and delivery, and transmission through close contact during feeding after delivery. Transmission during labor and delivery accounts for the majority of transmission. Intrauterine HBV infection is defined as the presence of hepatitis B virus replication markers measured at birth from peripheral venous blood collected from a newborn baby that has been consistently positive for at least 3 months. The lack of recent immunization effect, despite the use of combined active + passive immunization, is associated with high maternal HBsAg titers, HBsAg, HBeAg positivity and DNA positivity. Therefore, pregnant women carrying high loads of hepatitis B virus should be actively medicated during pregnancy for mother-to-child blockade.