The objective of this study is to assess the effectiveness of an operational strategy to prevent HBV mother-to-child transmission (MTCT) in Cambodia based on the use of rapid tests HBs Ag and HBe Ag to screen HBV infection and a treatment by TDF for patients with a positive HBeAg test with a "test and treat" strategy for those seen for Antenatal Care (ANC) from 24 weeks of amenorrhea. In all cases, vaccination of the newborn will be carried out according to the national protocol in Cambodia i.e. 4 injections at 24 hours, 6, 10 and 14 weeks of age.