Chronic HBV infection among pregnant women and their infants in Shenyang, China

BACKGROUND: The main transmission route of the hepatitis B virus (HBV) is mother to child transmission and contributes significantly to chronic HBV infection. Even though immunoprophylaxis with hepatitis B immunoglobulin (HBIG) and hepatitis B vaccine is administrated to neonates whose mothers are hepatitis B surface antigen (HBsAg) positive, about 10% of the neonates suffer from HBV infection in their early life. OBJECTIVES: To survey chronic HBV infection among pregnant women and their infants and analyze the reason for immunoprophylaxis failure. METHODS: Serum HBsAg was tested in all pregnant women. HBVDNA and other serum HBV markers including hepatitis B e antigen (HBeAg), hepatitis B core antibody (anti-HBc) and hepatitis B surface antibody (anti-HBs) were tested among HBsAg positive pregnant women. All infants whose mothers were HBsAg positive were vaccinated with a standard immunoprophylaxis. Serum HBV markers and HBVDNA were tested among these infants at 7 months of age. HBV genotypes were analyzed among the infants and pregnant women who were HBVDNA positive. RESULTS: The prevalence of HBsAg, anti-HBc and anti-HBs among 4,536 pregnant women was 5.49%, 29.65% and 58.55%, respectively. The prevalence of HBsAg, anti-HBc and anti-HBs among pregnant women older than 20 years of age was significantly different compared to pregnant women younger than 20 years of age (4.54, 5.69 and 0.61 times, prevalence older vs. younger, respectively. P<0.05, 0.01, 0.05, respectively). Among 249 HBsAg positive pregnant women, 167 (67.07%) were HBeAg positive, 204 (81.93%) were HBVDNA positive and only 37 (14.86%) had HBVDNA >10(7) IU/ml. Among the infants whose mothers were HBsAg positive, 214 (85.94%) infants were anti-HBs positive. There were 12 (4.82%) infants who were HBsAg and HBVDNA positive, and all 12 of these infants mothers were HBeAg positive and had HBVDNA >10(7) IU/ml. Genotypes B and C were present among 165 pregnant women and genotype C was present in 85 pregnant women. There were 12 infants who were HBsAg positive and had the same HBV genotypes as their mothers. There was a significant difference in genotypes between the pregnant women whose infants were infected with HBV compared to those without HBV infection (P < 0.05). CONCLUSIONS: There was a significant decline in HBsAg prevalence among pregnant women and their infants in Shenyang. Genotype C might be a risk factor for mother to child transmission of HBV.