OBJECTIVESTo analyze the relationship between the fetus infection and HBV M, HBV DNA in amniotic fluid, umbilical cord blood, maternal blood and placenta, and to explore the mechanism of vertical transmission of HBV.

METHODSImmunonetric assay and nucleic acid amplification hybri-comb were used. Both HBV M and HBV DNA were detected in amniotic fluid, vein blood, umbilical cord blood for each of 65 HBV-positive women in their different gestational periods, while immunohistochemical analysis was carried out on the tissue of placenta, liver, lung or heart from each abortive fetus/dead infant in the case.

RESULTSFor all of the 65 HBsAg-positive women in their different gestational periods, the detected positive rate of HBsAg was 21.50% in amniotic fluid, and 20.00% in umbilical blood. The positive rate of HBsAg, HBeAg, Anti-HBc and HBV DNA detected in blood, amniotic fluid and umbilical blood was 6.15%. The cases with positive HBsAg, Anti-HBe, Anti-HBc and negative HBV DNA were in a percentage of 13.85%. Immunohistochemical analysis on placentas after birth/abortion as well as the tissues of livers, lungs, hearts of the fetuses/dead infants in 4 cases of pregnant women with positive HBsAg, HBeAg, Anti-HBc or HBV DNA in blood, amniotic fluid or umbilical blood showed that HBsAg, HBcAg positive cells in the scope could be seen in every layer of the tissue of placenta, in the hepatic/pulmonary tissue, but not in the cardiac tissue.

CONCLUSIONThe infection in amniotic fluid or placenta relates to HBV infection in fetus; intrauterine HBV may result in infection in organs such as blood, liver, or lung of a fetus; infection in the amniotic fluid may be another key route of the intrauterine infection of fetus, and the detection on HBV M or HBV DNA in amniotic may be used as one of diagnostic proofs of HBV infection of fetus in its early stage.