[Epidemiology study of intrauterine transmission of HBV in HBsAg-positive parturients in Xi’an]

Objective: To investigate the current status and influence factors of HBV intrauterine transmission (BIT) in HBsAg-positive parturients and understand the outcome of HBV transmission and response to hepatitis B vaccine immunization in children in Xi’an. Methods: An epidemiological survey was conducted in 341 HBsAg-positive parturients who gave birth in Northwest Women and Children Hospital of Shaanxi Province from January 2015 to January 2018. Serological tests were performed by using venous blood from 344 newborns within 24 hours after birth and at the age of 1 year old. A nested case-control study was conducted to analyze the infection rates of intrauterine dominate HBV infection (DBI) and intrauterine occult HBV infection (OBI) in BIT and their influencing factors in newborns. The epidemiological survey was conducted to collect the information about the outcome of HBV transmission and the positive rate of HBsAb in children at high-risk from August 2016 to October 2018. Results: The BIT rate was 46.51 % (160/344) in HBsAg-positive parturients, the DBI rate was 8.14 % (28/344), the OBI rate was 38.37 % (132/344), and the odds ratio of DBI and BIT in neonates of HBeAg-positive parturients were respectively 2.60 (95 %CI : 1.19-5.70) and 2.21 (95 %CI : 1.36-3.61) times higher than that of HBeAg-negative parturients. The odds ratio of BIT in neonates with maternal peripheral blood HBV DNA load ≥200, ≥10(3) and>10(6) copies/ml were 1.99 (95 %CI : 1.29-3.08), 1.73 (95 %CI : 1.11-2.69) and 2.33 (95 %CI : 1.33-4.10) times higher than those in neonates with maternal peripheral blood HBV DNA<200,<10(3), and ≤10(6) copies/ml respectively. The incidence of DBI in neonates of parturients with placenta previa was 14.07 times higher than that of parturients without placenta previa (95 %CI : 1.23-160.76). The incidence of BIT in neonates of parturients who received no hepatitis B immunoglobulin during pregnancy was 1.60 times higher than that in neonates of those who received hepatitis B immunoglobulin (95 %CI : 1.02-2.53). Follow-up results showed that HBsAg negative conversion was found in 9 of 14 children with DBI, and 24.17 % (22/91) of children had OBI. The overall rate of immune response to hepatitis B vaccine was 69.23 % (63/91). The immune response rate in children with OBI was only 59.09 % (13/22). Conclusion: Newborns of HBsAg-positive parturients had high rate of OBI and lower rate of immune response to hepatitis B vaccine detected in follow-up, indicating a gap in hepatitis B prevention and control. HBV monitoring and intervention in HBsAg-positive women of childbearing age and hepatitis B antibody monitoring in children at high-risk are important measures to control infection source and protect susceptible population.