AIM:To examine the determinants of maternal-neonatal transmission of hepatitis B virus(HBV) METHODS:A nested case-control study was conducted in Changsha,Hunan,People’s Republic of China from January 1,2005 to September 31,2006 To avoid potential maternal blood contamination,we collected vein blood of newborns immediately after birth and before initial hepatitis B vaccination to determine the HBV infection status of the newborn For each HBsAg-positive infant,one HBsAg-negative infant born to an HBsAg-positive mother was matched by hospital at birth(same),gender(same),and date of birth(within 1 mo) A faceto-face interview was conducted to collect clinical and epidemiological data Conditional logistic regression analysis was used to estimate the independent effects of various determinants on maternal-neonatal transmission of HBV RESULTS:A total of 141 HBsAg-positive infants and 141 individually matched HBsAg-negative infants were included in the final analysis Maternal first-degree family history of HBV infection,intrahepatic cholestasis,and premature rupture of membranes were risk factors for perinatal transmission of HBV,whereas systematic treatment and HBV immunoglobulin injections for mothers with HBV infection were protective factors for maternal-neonatal transmission of HBV,after adjustment for potential confounding factors CONCLUSION:For HBsAg-positive mothers,systematic treatment,HBV immunoglobulin administration,and controlling intrahepatic cholestasis and pregnancy complications may reduce the incidence of perinatal transmission of HBV. AIM: To examine the determinants of maternal-neonatal transmission of hepatitis B virus (HBV) METHODS: A nested case-control study was conducted in Changsha, Hunan, People’s Republic of China from January 1,2005 to September 31,2006 To avoid potential maternal blood contamination, we collected vein blood of newborns immediately after birth and before initial hepatitis B vaccination to determine the HBV infection status of the newborn For each HBsAg-positive infant, one HBsAg-negative infant born to an HBsAg-positive mother was matched by hospital at birth (same), gender (same), and date of birth (within 1 month) A faceto-face interview was conducted to collect clinical and epidemiological data Conditional logistic regression analysis was used to estimate the independent effects of various determinants on maternal -neonatal transmission of HBV RESULTS: A total of 141 HBsAg-positive infants and 141 individually matched HBsAg-negative infants were included in the final analysis Maternal first-degree famil y history of HBV infection, intrahepatic cholestasis, and premature rupture of membranes were risk factors for perinatal transmission of HBV, were systematic treatment and HBV immunoglobulin injections for mothers with HBV infection were protective factors for maternal-neonatal transmission of HBV, after adjustment for potential confounding factors CONCLUSION: For HBsAg-positive mothers, systematic treatment, HBV immunoglobulin administration, and controlling intrahepatic cholestasis and pregnancy complications may reduce the incidence of perinatal transmission of HBV.