In order to have a healthy and smart baby, couples who want to have children are advised to have prenatal counseling and medical checkups, which include a hepatitis B virus test, or what we often call a two-and-a-half pair. Once found to be negative for hepatitis B virus antibodies (HBVAb) through the test, the woman can receive live attenuated hepatitis B virus vaccine, which can break the HBV couple-maternal-infant-population transmission chain, thus effectively preventing intrauterine transmission. It has been reported that two HBV ac20ug vaccinations during pregnancy resulted in an HBsAb positivity rate of 84% in newborns. I personally would like to make a special point that it is okay to get hepatitis B vaccination before or during early pregnancy, but to do so when you are in good health and have good immunity. I have seen a young mother-to-be in early pregnancy who became infected as a major triple-positive patient after receiving the vaccine in early pregnancy; she was very thin, worked hard and had low resistance. She ended up getting infected instead, which would have been bad. In February 2013, the Obstetrics and Gynecology Section of the Chinese Medical Association issued the Clinical Guidelines for Prevention of Mother-to-child Transmission of Hepatitis B Virus, which clearly states that hepatitis B infection should be clarified before pregnancy, and those with chronic HBV infection must have their liver function checked regularly after pregnancy, especially in early and late pregnancy. The so-called chronic HBV infected person is defined as a person who has been HBsAg positive for more than 6 months. If the liver function is normal, the person is a chronic HBV carrier. HBsAg(+)HbeAg(-) is a minor triplet, and HBsAg(+)HBeAg(+) is a major triplet, and the intrauterine infection rate of mother-to-child vertical transmission is <3%, mostly seen in pregnant women with major triplet. Without immunoblocking measures, 90% of babies born to HBeAg positive mothers will become chronically infected with HBV. However, even with hepatitis B immunoglobulin (HBIG) and vaccination, there is still a high probability of vertical transmission among infants born to high viral load and HBeAg-positive mothers. Then, the Guidelines state that pregnant women who are chronic hepatitis B carriers without clinical symptoms of hepatitis can have their liver function reviewed every 1-2 months during pregnancy, and if alanine transferase (alt) levels are moderately elevated (more than twice the normal high limit, >80u/L,) or if bilirubin levels are elevated, they need to be hospitalized as appropriate. hospitalization, consultation with a gastroenterologist, or even termination of pregnancy. Pregnant women who do not have hepatitis B should also have their hepatitis B half-checked every 3 months to avoid being unaware of a new hepatitis B virus infection. Can the application of high potency immunoglobulin (HBIG) during late pregnancy interrupt and prevent mother-to-child transmission? Although it has been suggested that the application of HBIG during late pregnancy in HBV-infected pregnant women can prevent intrauterine infection in the fetus, studies in evidence-based medicine have found that the findings supporting these arguments lack rigorous evidence and that HBIG injected at 200-400 U every 4 weeks during late pregnancy cannot reduce HBV viral load or reduce mother-to-child transmission, so the latest prevention guidelines do not recommend that HBIG must be applied during late pregnancy. The conclusions in this regard are controversial and require further medical evidence in larger samples. Does cesarean delivery during labor reduce mother-to-child transmission? The answer is also no! Recent studies have shown that there is no statistically significant difference in the prevalence of HBV infection in neonates born by cesarean section compared to those born spontaneously after formal prophylaxis in chronically infected pregnant women. This suggests that cesarean delivery does not reduce mother-to-child transmission of HBV and that it is not necessary to perform cesarean delivery simply because of chronic hepatitis B carriage. The use of antiviral therapy to prevent mother-to-child transmission in HBeAg-negative infected pregnant women is not necessary, and the question of whether to treat HBeAg-positive infected pregnant women with anti-HBV in mid- to late-pregnancy remains to be answered in a multicenter randomized controlled study with a large sample. Routine anti-HBV treatment in pregnant women with Hepatitis B virus infection with abnormal liver function is also not recommended, and strict indications for treatment should be followed. In summary, it becomes clearer that there is no single ideal method for performing intrauterine blockade. Vaccination of newborns born to mothers with chronic hepatitis B carriers is the most effective measure at present. How is hepatitis B prevention administered to newborns after birth? The active ingredient of hepatitis B vaccine is HBsAg. After the 1st vaccination, most anti-HBs are still negative or below the lower limit of detection; the anti-HBs will turn positive only about l week after the 2nd vaccination, i.e. 35~40d after the start of vaccination to have immunity to HBV; the 3rd vaccination can make the level of anti-HBs significantly higher and prolong the protection years. The anti-HBs positive conversion rate of newborns after full-term vaccination is as high as 95%~100%, and the protection period can be more than 22 years. Therefore, for full-term newborns, when the pregnant woman is HBsAg-negative, regardless of HBV-related antibodies, the vaccine is administered according to the “0, 1, 6 months” protocol, and HBIG is not necessary; when the pregnant woman is HBsAg-positive, regardless of whether the HBeAg is positive or negative, the newborns must receive HBIG and full vaccination in time. HBIG needs to be administered within 12 hours after birth (theoretically, the earlier the better), and its active ingredient is anti-HBs, which starts to work 15-30 min after intramuscular injection, and the protective anti-HBs can be maintained for at least 42-63 d. At this time, anti-HBs are actively produced in the body, so there is no need for the second injection of HBIG. After taking the above formal preventive measures, the protection rate for newborns of HBsAg-positive and HBeAg-negative pregnant women is 98%-100%, and the protection rate for newborns of both HBsAg and HBeAg-positive pregnant women is 85%-95%, while the overall protection rate is only 55%-85% if HBIG is not used and only the vaccine is applied. For premature infants with immature immune system, 4 doses of hepatitis B vaccine are usually required. If the vital signs of preterm infants are unstable, they should first be treated for relevant diseases and then be vaccinated according to the above-mentioned program after stabilization. If the premature infant is <2000g< span="">, the first vaccination should be given after the body mass reaches 2000g (if the body mass does not reach 2000g before discharge, the first vaccination should be given before discharge); after l~2 months, the vaccination should be re-administered according to the 3-vaccination protocol at 0, 1 and 6 months. HBIG must be given intramuscularly within 12 h after birth to premature infants of HBsAg-positive pregnant women, regardless of their physical condition, and another injection is required after an interval of 3~4 weeks. If the vital signs are stable, there is no need to consider the body mass, and the first vaccination is given as soon as possible; if the vital signs are unstable, the first vaccination is given as soon as possible after stabilization; after 1 to 2 months or after the body weight reaches 2000 g, the vaccination is then reintroduced according to the 3-dose protocol for 0, 1 and 6 months.