The main cause of hepatitis B in children is mother-to-child transmission. In fact, in Asian countries, this is a common route of transmission of hepatitis B because people's knowledge about the disease is limited, and many people are not fully vaccinated. In Vietnam, many women have not been screened for the disease before and during pregnancy. According to some studies, in Vietnam, more than 10% of pregnant women are infected with the hepatitis B virus. This is a very high rate.