This prospective study evaluated the viability of telbivudine for blocking mother-to-child transmission (MTCT) of hepatitis B virus (HBV) infection.Pregnant women positive for the hepatitis B surface antigen began telbivudine treatment before 14 weeks of gestation (i.e., early), between 14 and 28 weeks of gestation (late), or not at all (control). In the late-treatment group, 55 women terminated telbivudine therapy within puerperium. All neonates underwent routine hepatitis B immunoglobulin plus vaccination. Mothers and infants were followed for 7 months after birth.Pregnancy outcomes were similar among the 3 groups. HBV MTCT rates in the early and late treatment and control groups were 0, 0, and 4.69%, respectively. The rates of infant vaccination success among the 3 groups were similar, as were neonatal outcomes including birth weights, asphyxia, hyperbilirubinemia, Apgar score, birth defects, and weight and height at 7 months. Puerperal discontinuation of telbivudine did not increase the alanine transaminase value at 7 months after birth, but increased serum HBV DNA levels, and rates of positive hepatitis Be-antigen.Telbivudine treatment in HBV-infected pregnant women was associated with lower serum HBV DNA levels and reduced rates of HBV MTCT; there were no associated changes in pregnancy or neonatal outcomes at birth or 7 months after birth, or in the rate of infant vaccination success. Puerperal drug withdrawal after short-term antiviral therapy will not influence hepatic function, but may increase virus replication.