pediatrics
Neonatal Hepatitis B Virus (HBV) Infection
Etiology of Neonatal HBV Infection
HBV infection occurs during delivery from an infected mother. The risk of transmission is 70 to 90% from women seropositive for hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg— see Serology ) at the time of delivery. Women without the e antigen or with anti-HBe transmit the infection only 5 to 20% of the time. Mother–infant HBV transmission results primarily from maternofetal microtransfusions during labor or contact with infectious secretions in the birth canal. Transplacental transmission is identified in < 2% of infections. Postpartum transmission occurs rarely through exposure to infectious maternal blood, saliva, stool, urine, or breast milk. Up to 90% of infants infected perinatally will develop chronic infection, and perinatally acquired HBV infection may be an important viral reservoir in certain communities. 