[The effect of maternal HBV DNA levels on HBV intrauterine transmission and fetal distress].

Aim: To identify the key risk factors of intrauterine hepatitis B virus transmission (HBV) and its effect on the placenta and fetus.

Methods

425 infants born to hepatitis B surface antigen (HBsAg)-positive pregnant women who received combined immunization with hepatitis B immunoglobulin and hepatitis B vaccine between 2009 to 2015 were prospectively enrolled in this study. The intrauterine transmission situation was assessed by dynamic monitoring of infants HBV DNA load and quantitative HBsAg. Univariate and multivariate regression analysis was used to determine the high risk factors for intrauterine transmission. Stratified analysis was used to determine the relationship between maternal HBV DNA load and fetal distress. Transmission electron microscopy was used to observe HBV Effects on placental tissue.

Results

HBV intrauterine infection rate was 2.6% (11/425). Multivariate analysis result showed that the maternal HBV DNA load was an independent risk factor for intrauterine infection among infants (P=0.011). Intrauterine infection and distress rate was significantly higher in infants with with maternal HBV DNA>106 IU/ml than those with HBV DNA <106 IU/ml (12.2% vs. 1.8%; χ2=11.275, P=0.006), and (24.4% vs. 16.0%, χ2=3.993, P=0.046). Transmission electron microscopy showed that mitochondrial edema, endoplasmic reticulum expansion and thicker basement membrane were apparent when the maternal HBV DNA>106 IU/ml than that of maternal HBV DNA<106 IU/ml (960 nm vs. 214 nm, Z=-2.782, P=0.005) in the placental tissue.

Conclusion

Maternal HBV DNA>106 IU/ml is associated not only with intrauterine infection, but also with increased incidence of intrauterine distress and placental sub-microstructural changes, providing strong clinical and histological evidence for pregnancy avoidance and treatment in this population.