Mother-to-child transmission (MTCT) is one of the most important routes of transmission of the hepatitis B virus, and the majority of hepatitis B carriers in past years were infected as a result of parent-to-child transmission. Studies have shown that if no interruption measures are implemented, about 40% of babies born to HBsAg-positive mothers become HBsAg-positive within 6 months, and the HBSAg-positive rate of babies born to double-positive mothers of both HBsAg and HBeAg can be as high as 90% or more. Therefore, it is best for mothers with hepatitis B to stabilize their condition before getting pregnant, and they should take measures to prevent mother-to-child transmission before and after delivery. First, the following to understand the mother of hepatitis B through which path transmission to the baby: 1, intrauterine infection: due to HBV so that the placental barrier is damaged or permeability changes. Studies have shown that HBV-DNA positivity in maternal blood is a major factor in mother-to-child transmission. Regardless of maternal HBeAg positive or negative, the risk of fetal infection increases with the increase in maternal serum HBV-DNA content. Therefore, serum HBV-DNA is an important indicator of intrauterine infection. 2.Partum infection: refers to the infection that occurs between the beginning of labor and the end of delivery. Due to the fetus in the birth canal, swallowing HBV-containing mother’s blood, amniotic fluid or vaginal secretions, etc.; or the uterine contraction during labor and delivery to make the placenta chorionic vascular rupture, the mother’s blood penetrate into the body of the fetus due to. In the mother-to-child transmission pathway occupies a high proportion. 3, postnatal infection: mainly through mother-child contact to make the virus infected newborns, and contact with the mother’s saliva and breastfeeding. Now it has been confirmed that the detection rate of HBV-DNA in the breast milk of mothers with hepatitis B teratitis III is 100%. However, experts believe that HBeAg carriers breastfeeding newborns to increase the rate of infant viral carriage is limited, than the delivery of the chance of infection is low. Second, what measures should be taken by the mother of hepatitis B? 1.Active anti-virus: reducing the level of HBV-DNA in pregnant women is the key to affecting the chance of transmission. Therefore, before pregnancy, we should actively treat hepatitis B, reduce serum HBV-DNA level, minimize vertical transmission from mother to child. 2, obstruction during delivery: whether cesarean section can reduce the incidence of mother-to-child transmission is inconclusive, but experts tend to advocate vaginal delivery, avoid perineal circumcision and reduce local fetal injury during delivery can reduce the chance of infection. 3.Combined immunization: after birth, newborns should be immunized with hepatitis B vaccine and HBIG for active and passive immunization to reduce the incidence of mother-to-child transmission. Infants born to mothers with hepatitis B should be subjected to active and passive immunization, i.e. intramuscular injection of HBIG 100 international units immediately after delivery, which is required to be carried out as early as possible, no later than 16 hours after birth, and preferably within 6 hours, and at the same time, hepatitis B vaccine can be injected into the other limb. HBIG can be given once a month for 3-6 consecutive months, and the vaccine against hepatitis B adopts the program of 1-2-6 to be vaccinated. 4, postpartum blockade: breastfeeding babies is the best way of feeding, but there is no consensus on whether mothers with chronic hepatitis B can breastfeed. Most experts believe that breastfeeding mothers who are positive for hepatitis B surface antigen does not increase the risk of infant infection. Therefore, newborns can breastfeed as long as they have received hepatitis B immune globulin and hepatitis B vaccine within 12 hours of birth. However, breastfeeding is preferably prohibited for mothers with very high serum or breast milk HBV-DNA, broken nipples, and infants with oral mucosal ulcers or broken skin around the mouth, even if the infant has received combined immunization with HBIG and hepatitis B vaccine.