Background: Maternal-infant transmission of hepatitis B virus(HBV) occurs even after passive-active immunization.\nSome scholars speculate that in-utero infection may be the main cause of immunoprophylaxis failure. However,\nthere is a lack of evidence about the possible occurrence periods of perinatal transmission.\nMethods: From 2008 to 2012, 428 pairs of HBsAg-positive mothers and neonates were enrolled and 385 infants\naged 8ââ?¬â??12 months were followed. HBV markers (HBsAg, anti-HBs, HBeAg, anti-HBe, anti-HBc, HBV-DNA) were\nperformed on all subjects.\nResults: Of mothers who were positive for HBsAg, HBeAg, HBV-DNA, 35.1 %, 94.3 %, 12.7 % of their neonates were\npositive for those indices, respectively. Neonatesââ?¬â?¢ mean titers of those indices were significantly lower than their\nmothersââ?¬â?¢. There were no significant differences in rates of positivity and mean titers of anti-HBe and anti-HBc\nbetween neonates and mothers. Most of the positive indices turned negative during the follow-up period.\nImmunoprophylaxis failed in seventeen infants: four infants had HBV-DNA > 6 log 10copies/mL both at birth and\nin follow-up; in six infants, mean viral load was 3.72 Ã?± 0.17 log 10copies/mLat birth and 7.62 Ã?± 0.14 log 10copies/\nmL at follow-up; seven infants were HBV-DNA negative at birth but were found to have > 6 log 10copies/mL\nduring follow-up. Infants that were immunoprophylaxis failures were all born to HBeAg-positive mothers with\nHBV-DNA > 6 log 10copies/mL.\nConclusions: The placental barrier can partly prevent maternal HBsAg, HBeAg, HBV-DNA from passing through\nto fetus. Performing HBsAg, HBeAg, HBV-DNA once at birth can neither diagnose nor exclude maternal-infant\ntransmission. The diagnosis of infection period depends on the dynamic changes in viral load from birth through\nthe follow-up period but whether the infection occurred in utero, at delivery or during the neonatal period could not\nbe determined.
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