Occult hepatitis B virus infection in pregnant woman and its clinical implication.

Background/aims: The objective of this study was to document the prevalence rate of occult hepatitis B virus (HBV) in healthy pregnant woman and the possibility of transmission to the foetus.
Methods: This study was performed prospectively with 202 healthy pregnant women. HBV-DNA testing was performed using two specific quantitative tests with two independent sets of sera and cord blood. DNA sequencing analysis was carried out to confirm the specificity of polymerase chain reaction (PCR) product of HBV-DNA testing.
Results: Eight of 202 (4%) individuals with the TaqMan PCR assay and 23 of 202 (11.4%) with the COBAS Amplicor HBV Monitor test were HBV-DNA positive. Six (3%) individuals were positive with both methods. Sequencing and genotyping analysis of HBV polymerase gene with sera of the 75th subject resulted in genotype C. HBV-DNA testing with four cord blood samples showed that all were HBV-DNA negative.
Conclusion: Occult HBV infection shows a difference in prevalence rate depending on the test method but the existence has been confirmed by sequencing analysis. Our results also suggest that vertical transmission through the cord blood is not so high as to be clinical problems and warrants further investigation.