Perinatal transmission of hepatitis B virus from mother to child has serious consequences. It occurs mainly in mothers who are double positive for HBsAg and HBeAg. Once a newborn is infected, most of them will become chronic asymptomatic HBsAg carriers. Preventive methods: First, it is best to do prenatal testing for hepatitis B surface antigen and e antigen, and make preparations for labor and delivery for those who are double-positive. Prevent preeclampsia and terminate the pregnancy in this case.