AIM:To evaluate the efficacy and safety of lamivudinetreatment of chronic hepatitis B disease in pregnancy.METHODS:The study group was comprised of 38 chronicHBV patients who were diagnosed pregnant duringIamivudine treatment and voluntary to continue the sametherapy.The control group was from documented patientdata in the literatures.We compared the followingparameters with those of a control group:anti-HBV efficacy,complications of pregnancy (abortion,preterm birth,neonatalasphyxia,fetal death,and congenital anomaly),incidenceof HBV-positive babies and developmental anomalies inpregnant women treated with Iamivudine.RESULTS:The blocking rate of lamivudine treatment wassignificantly higher than that of active vaccine immunizationfor babies with double-positive (HBsAg/HBeAg) mothers with30-30-10 μg doses of vaccine (74.07%) and with 30-20-10 μg(64.87%).The natural vertical HBV transmission from motherto infant of “double-positive”mothers was 100% (10/10).No pregnancy complication was noted during the observationperiod,but in the control group the incidences of pregnancycomplication were 16.67% (abortion),43.02%(preterm),15.62% (neonatal asphyxia),and 4.49% (fetal death),10.0% (congenital anomaly).No HBV-positive newborn wasdetected and no developmental anomaly was found in thestudy group.CONCLUSION:Lamivudine is helpful to prevent maternal-infant HBV transmission and may reduce the complicationsof HBV-infected pregnant patients. AIM: To evaluate the efficacy and safety of lamivudinetreatment of chronic hepatitis B disease in pregnancy. METHODS: The study group was comprised of 38 chronicHBV patients who were diagnosed pregnant during Iivivudine treatment and voluntary to continue the same treatment. The control group was from documented patient data in the literatures. We compared the following parameters with those of a control group: anti-HBV efficacy, complications of pregnancy (abortion, preterm birth, neonatalasphyxia, fetal death, and congenital anomaly), incidence of HBV-positive babies and developmental anomalies inpregnant women treated with Iamivudine .RESULTS: The blocking rate of lamivudine treatment wassignificantly higher than that of active vaccine immunization for babies with double-positive (HBsAg / HBeAg) mothers with 30-30-10 μg doses of vaccine (74.07%) and with 30-20-10 μg (64.87%). The natural vertical HBV transmission from motherto infant of “double-positive” mothers was 100% (10/10) .No pregnancy complication was noted during the observation period, but in the control group the incidences of pregnancy complications were 16.67% (abortion), 43.02% preterm, 15.62% (neonatal asphyxia), and 4.49% (fetal death), 10.0% (congenital anomaly). No HBV-positive newborn wasdetected and no developmental anomaly was found in the study group.CONCLUSION: Lamivudine is helpful to prevent HBV infection in maternal-infant and may reduce the complicationsof HBV-infected pregnant patients.