Mechanism and Antiviral Therapy in Preventing Mother-to-Child Transmission During Pregnancy with Hepatitis B Virus Infection

Context: Mother-to-child transmission (MTCT) is one of the main transmission routes of chronic hepatitis B virus (HBV) infection. The successful rate of preventing MTCT has increased to over 90% after the administration of passive-active immunoprophylaxis (vaccine and hepatitis B immunoglobulin (HBIG)) on infants born to hepatitis B surface antigen (HBsAg)-positive mothers. However, 5%-10% of the infants had chronic HBV infection who were born to mothers with high HBV DNA levels. Therefore, the current domestic and international guidelines recommended that antiviral therapy in late pregnancy was to further decrease the MTCT rate. This study aimed at reviewing the mechanisms of MTCT and controversial issues in antiviral therapy for pregnant women with high viral load in order to provide clinicians with some strategies for preventing MTCT of HBV. Evidence Acquisition: Relevant English published papers were searched using online databases, including PubMed and EMBASE from January 2000 to January 2019. We summarized the findings of 61 relevant studies in this review. Results: The mechanism of MTCT is still unclear and further studies are needed. Antiviral therapy for pregnant women with high viral load can reduce the rate of MTCT and provide the appropriate safety for mothers and infants. Conclusions: The mechanisms underlying MTCT of HBV is still unknown and more investigations are required. The efficacy and safety of taking tenofovir disoproxil fumarate (TDF) orally in pregnant women with high viral load in the second or third trimester of pregnancy to block MTCT of HBV have been proved. The withdrawal of antiviral therapy during pregnancy due to MTCT should not exceed 3 months after delivery at the latest. Most pregnant women tend to suffer from increased alanine aminotransferase (ALT) after discontinuing antiviral drugs during pregnancy. Accordingly, close ALT levels monitoring after drug discontinuation is essential.