During my hepatitis clinics, I often encounter young couples of childbearing age with hepatitis B who ask the same question: Can we have children? Is there a risk of passing the hepatitis B virus to our children? What should we do? This is a question that has been troubling me for a long time, and by looking up the literature online, I would like to present the current relevant research advances in the hope that they can provide some help. As we all know, hepatitis B is an infectious disease that seriously endangers human health, and epidemiology confirms the existence of mother-to-child transmission of hepatitis B virus, and mother-to-child transmission is of great importance in the transmission route of hepatitis B. Newborns can be infected with hepatitis B through intrauterine and perinatal vertical transmission, and can also be infected with hepatitis B virus from their mothers through horizontal transmission after birth. In addition, it is believed that fetuses of HBsAg-negative mothers and HBsAg-positive fathers are likely to be infected with HBV through the route of vertical transmission from father to child. Therefore, cutting off this route is an important measure to control HBV infection. First, let us understand the mechanism of vertical transmission from mother to child. 1, intrauterine transmission: HBV intrauterine infection rate of 13%-14%. the mechanism of HBV through the placental barrier is still unclear, may be caused by damage to the placental barrier or permeability changes caused by leakage of maternal blood. HBV intrauterine infection may have two routes: (1) hematogenous: due to preterm labor and other causes of placental vascular damage, so that the maternal blood containing high levels of HBV directly into the fetal circulation caused by infection. (2) cellular origin: HBV first infects the meconium cells of pregnant women, then through “cellular transfer”, and finally infects the endothelial cells of the fetal chorionic capillaries causing intrauterine transmission. 2, transmission during delivery: HBV infection during delivery is one of the main ways of mother-to-child transmission, accounting for about 40% 60%. Fetus through the birth canal swallowed mother’s blood containing HBV, amniotic fluid and secretions from the birth canal, or in the process of delivery due to uterine contractions to rupture the placental villi vessels, a small amount of maternal blood leakage into the fetal blood circulation caused. It is believed that the chance of HBV-positive maternal blood leaking into the fetal blood circulation is closely related to the length of labor, while the fetus delivered by cesarean section does not pass through the birth canal, which can avoid or reduce fluid contact with the mother and reduce the chance of infection, and the mother has not yet entered labor after the operation, so the intensity of uterine pain is weaker, shorter or no uterine pain. It reduces the maternal blood entering the fetal blood circulation due to the rupture of the placental vessels, but some studies have also shown that the preventive effect of cesarean delivery is small, and there is much intraoperative bleeding, and the infant is exposed to a large amount of infected maternal blood, so cesarean delivery cannot reduce the rate of HBV infection in newborns. 3, postpartum transmission: postpartum neonatal HBV infection is closely related to the mother’s infectivity, HBV marker-positive mothers have a high rate of HBV-DNA detection in blood, amniotic fluid, secretions and colostrum, and most postpartum infections are acquired from body fluids such as breast milk or saliva containing HBV. There are different opinions on whether to breastfeed HBsAg(+) or HBsAg and HBeAg double-positive patients. Most scholars believe that breastfeeding is contraindicated when the mother’s blood is positive for HBV-DNA. Once the pathogenesis of vertical mother-to-child transmission is understood, targeted preventive measures should be taken to minimize the transmission rate. The following describes the current measures and effects suitable for mother-to-child interruption. 1. Establish a comprehensive perinatal health care system: screen, manage and monitor pregnant women with HBV infection, and test and follow up newborns to determine whether they are fetus infected. There is no conclusive evidence that hepatitis virus can cause fetal malformations, however, there are reports of increased incidence of congenital dysmorphism, and early pregnant women with high HBsAg titers and HBeAg positivity are advised to terminate the pregnancy. newborns of HBV-infected pregnant women are showered immediately after birth, and breastfeeding is stopped and the mother is isolated for 4 weeks. 2. Immunoprophylaxis: (1) Passive immunization (HBIG injection): the placenta has the function of actively transmitting IgG-type antibodies from the mother to the fetus after 20 weeks of pregnancy. At present, it is believed that the rate of intrauterine infection in newborns can be effectively reduced after multiple injections of HBIG in pregnant women before delivery. It also reduces the maternal blood HBsAg titer, and no adverse effects were found during the follow-up of HBIG injection before and after delivery. (2) Neonatal hepatitis B immunoprophylaxis ① Passive immunization (HBIG injection): HBIG is a high-efficiency anti-HBV immunoglobulin, which can neutralize the virus entering the body, avoid and reduce the occurrence of HBsAg chronic carriers, and can effectively prevent and block HBV infection after blood transfusion, the earlier HBIG is used the better, it can be injected intramuscularly l ml immediately after birth, HBeAg-positive people in Immediately 1 month and 6 months each injected l ml, generally within 12 months have some protection. ② Active immunity and active immunity plus passive immunity: After hepatitis B vaccination, about 95% of people have protective antibodies to HBsAg (anti-HBs). Newborns also have sufficient antibody effect against hepatitis B. Newborns of HBsAg-positive pregnant women need to be vaccinated with hepatitis B vaccine within 24h, 1 month and 6 months after birth, and many studies suggest that active immunization of newborns with hepatitis B vaccine and blocking mother-to-child transmission can achieve more satisfactory results. However, most scholars advocate the combined application of HBIG and hepatitis B vaccine, both for immediate postnatal passive immunization of the newborn, and for subsequent active immunization of the infant with anti-HBs. continuous protection, but immunoprophylaxis is only effective for mother-to-child transmission during and after delivery, and is not ideal for intrauterine infection. 3, antiviral drugs to block mother-to-child transmission of HBV: reduce the level of virus in the mother’s blood is the key to reducing mother-to-child transmission of HBV, the current clinical application of anti-HBV treatment drugs are interferon and lamivudine. Interferon has not been reported on the application of interferon antiviral during pregnancy to reduce the rate of mother-to-child transmission because of the high cost of treatment, low response rate for those with normal ALT levels, many side effects of treatment, and unclear effects on the fetus. Lamivudine can significantly inhibit DNA replication and rapidly reduce serum HBV-DNA. The results of most studies have shown that lamivudine given in the second trimester, i.e., the last month of pregnancy, is safe for the fetus and can improve the effectiveness of combined active and passive immunization in hypervirulinaemic pregnant women and reduce the rate of mother-to-child transmission of HBv. There are also reports about the failure of lamivudine to block mother-to-child transmission of HBv. 4, on the issue of cesarean delivery: Although cesarean delivery can avoid fetal inhalation of infected obstetric secretions during delivery, the study found that cesarean delivery has little preventive effect, and there is much intraoperative bleeding and the infant is exposed to large amounts of infected maternal blood, so cesarean delivery cannot reduce the rate of hepatitis B virus infection in newborns, and chronic HBV infection in mothers should not be used as an indication for cesarean delivery, especially for HBeAg and HBV The mother’s chronic HBV infection should not be an indication for cesarean delivery, especially for HBsAg-carrying mothers who are negative for both HBeAg and HBV-DNA. In summary, we have described the pathogenesis of vertical mother-to-child transmission, and although some mechanisms are still not completely clear, it is clear that mother-to-child transmission plays an incalculable role in the transmission of hepatitis B. Although we have taken some interruption measures, complete interruption cannot be performed 100% of the time, mainly because intrauterine infection has become a difficult point in the prevention of mother-to-child transmission of HBV. Related research will continue.