The main cause of chronic HBsAg carriage is mother-to-child transmission. The aim of the study was to determine the epidemiological, clinical and biological aspects of mother-to-child transmission of the hepatitis B virus in newborns of HBsAg-positive mothers. Methodology: This was a descriptive cross-sectional study which took place from 1 March 2020 to 30 June 2021 at the CSREF in Commune V. Sampling was exhaustive, and all newborns whose mothers were carriers of hepatitis B were included in the study. Results: One hundred and twenty newborns out of 3197 referred from the maternity unit, representing a frequency of 3.7% of hepatitis B in pregnant women. Eighty newborns were included. The other 40 were not included because the mothers refused. Among the mothers, 11/80 tested positive for HBeAg and anti-HBs, with 2 positive results (18.18%). Twelve pregnant women had viral load tests, with two positive results (16.66%). Six of the 80 pregnant women had received tenofovir during pregnancy (7.5%), and all the newborns had negative HBsAg results at 4 months of age. Conclusion : Low realization of viral markers of hepatitis B and treatment during pregnancy.