China is known as a country with a large hepatitis B population. Statistics show that there are as many as 130 million hepatitis B virus carriers in China, meaning one in every ten people is affected.Although China has a large number of hepatitis B cases, not all infections result from contact with patients. The vast majority (about 80%) originate from familial vertical transmission. Therefore, hepatitis B has been listed by the National Center for Disease Control and Prevention as one of the key diseases under surveillance. Effective prevention of this disease must start with blocking vertical transmission of the hepatitis B virus, thereby controlling the disease effectively at its source.
Vertical transmission of HBV encompasses both mother-to-child and father-to-child transmission. Extensive research has been conducted globally on the pathways of mother-to-child vertical transmission and corresponding prevention methods.
Recent domestic studies indicate that even when the mother is not a HBV carrier, her newborn may still become infected through vertical transmission.Experts explain that paternal transmission actually carries a higher risk than maternal transmission and is more likely to result in lifelong carrier status. However, paternal transmission is still classified as an infectious process rather than a genetic disorder. Effective treatment can interrupt this vertical transmission. What exactly is paternal transmission?
In men with hepatitis B, HBV DNA can be detected in their sperm. The virus resides in the cytoplasm of the sperm head. When sperm enters the egg cell, even if the mother has no hepatitis, the hepatitis B virus continues to replicate during the embryo formation process. This results in the offspring becoming either a hepatitis B patient or a virus carrier. Therefore, this mode of hepatitis B virus transmission is called father-to-child transmission.
Paternal-infant transmission differs from maternal-infant transmission. Research indicates that sperm from fathers infected with hepatitis B already carry HBV DNA fragments. These fragments reside in the cytoplasm of the sperm head. Through fertilization, they can replicate within the offspring's cells, causing infection and resulting in paternal-infant transmission of hepatitis B.Furthermore, even if no HBV infection occurs during fertilization, the pregnant woman remains at risk of contracting the virus from her husband throughout the pregnancy. Close daily contact and sexual activity during pregnancy can expose the mother to HBV infection, which may then be transmitted to the offspring via the father-mother-infant route. This constitutes an indirect form of father-to-child transmission.
When the father is HBeAg-positive and HBeAg-negative, the infection rate for his offspring can exceed 80%. When the father is HBeAg-positive, the infection rate for his offspring is approximately 20%.Fetal infection with HBV not only risks developing into hepatitis B disease or chronic carrier status but also impairs normal fetal growth and development. It may lead to low birth weight, congenital disorders or malformations, miscarriage, or stillbirth. Therefore, we must give sufficient attention to father-to-child transmission of HBV.
If the spouse is healthy and the HBV-infected individual is HBsAg-positive, or presents as "small three positives" or "small two positives," with HBV-DNA negative status, no clinical symptoms, normal liver function, and no abnormalities detected on liver/spleen ultrasound, this indicates HBV is not replicating in the body and has extremely low infectivity. Such HBV carriers are suitable for marriage.
Since direct mother-to-child transmission occurs at the germ cell stage, the most effective method to prevent hepatitis B transmission is preconception intervention.
I.Newlywed couples should undergo hepatitis B testing before marriage. If either partner has hepatitis B, active treatment should be pursued. Marriage and childbearing should only occur after the condition is cured with no infectious risk or is stable. If the mother successfully achieves immunity through hepatitis B vaccination before pregnancy, with HBsAb levels reaching 400 units or higher, this represents the optimal time for conception. This effectively protects both the mother and newborn, significantly reducing the likelihood of hepatitis B virus infection.
II. During pregnancy, starting from the 20-week prenatal checkup, administer 200 IU of hepatitis B immune globulin intramuscularly every 4 weeks. This effectively neutralizes hepatitis B virus in the mother's blood, further enhancing her resistance to infection from her husband's hepatitis B virus while reducing the risk of father-to-mother-to-infant transmission.
III. Newborns born to parents who are HBV carriers should receive the standard hepatitis B vaccine series. Additionally, they should receive high-potency hepatitis B immunoglobulin (100 IU) within 24 hours of birth and again at one month of age to provide enhanced protection.
Therefore, we emphasize that in cases where only the father has documented HBV infection, enhanced education is crucial. This ensures a deeper understanding of HBV transmission, enabling better cooperation with medical professionals to implement appropriate preventive measures for both the mother and offspring against paternal HBV infection.