Presence of hepatitis B virus markers in umbilical cord blood: Exposure to or infection with the virus?

We aimed to clarify whether presence of hepatitis B virus (HBV) markers in cord blood indicates exposure to or infection with HBV. We prospectively recruited HBsAg-positive pregnant women and their neonates 2012 through 2015. All neonates received postnatal immunoprophylaxis. The infants were followed up at 7–14 months of age. Totally 329 HBsAg-positive pregnant women and 333 neonates were enrolled. No cord blood was anti-HBc IgM positive. A total of 290 (87.1%) neonates were followed up at 7–14 months of age and 6 (2.1%) of them were infected with HBV. Of 146 neonates born to HBeAg-negative mothers, 38 (26.0%) and 30 (20.5%) had detectable HBsAg and HBV DNA in cord blood respectively, but none of 126 infants followed up was infected. Of 187 neonates born to HBeAg-positive mothers, 92 (49.2%) and 79 (42.2%) had detectable HBsAg and HBV DNA in cord blood respectively; 6 (3.7%) of 164 infants followed up were infected. Of seven neonates with HBV DNA > 10⁵ IU/ml in cord blood, four had no infection and three others were infected. Presence of HBsAg and/or HBV DNA, even at high levels, in cord blood just indicates exposure to, but not infection with HBV. Presence of HBV markers in cord blood cannot define intrauterine infection. [ABSTRACT FROM AUTHOR]