[Molecular epidemiological study of the relationship between hepatitis B virus genotype in pregnant women and intrauterine transmission].

Objective: To explore the hepatitis B virus (HBV) genotype carrier status of women of childbearing age in Xi'an, to obtain the association between pregnant women's HBV genotype and intrauterine transmission of HBV, and to analyze the possible influence of pregnant women's HBV infection characteristics and other factors on intrauterine transmission. Methods: A total of 240 HBsAg-positive pregnant women and their newborns in Xi'an from 2015-2017 were included in the epidemiological survey, and the levels of HBV and HBV DNA in the peripheral blood of pregnant women and the venous peripheral blood of newborns 24 hours after birth were detected by ELISA and real-time fluorescence quantitative PCR; the target fragments of the peripheral blood of pregnant women in the HBV S region target fragment amplification by nested PCR to determine the HBV genotype; binary logistic regression analysis model was used to complete the multifactorial analysis. Results: According to the HBsAg status and HBV DNA level in peripheral blood of newborns, 115 cases (47.92%) were classified into the group of non-intrauterine transmission of HBV, 95 cases (39.58%) into the group of occult intrauterine transmission (OBT) of HBV and 30 cases (12.50%) into the group of dominant intrauterine transmission (DBT) of HBV. Pregnant women's HBV genotypes were 80.42% C, 14.58% B, and 5.00% D. HBV B genotype significantly increased the risk of OBT (OR=2.22, 95%CI: 1.01-4.88), while C and D genotypes have a significant protective effect against OBT (OR=0.34, 95%CI: 0.15-0.78; OR=0.10, 95%CI: 0.02-0.56). Maternal HBV DNA (OR=1.15, 95%CI: 1.07-1.24) is an independent risk factor for DBT. Concurrent positivity for HBsAg, HBeAg, and anti-HBc ("triple Ⅲ") (OR=2.24, 95%CI: 1.05-4.80) is an independent risk factor for OBT. Conclusions: In Xi'an, intrauterine transmission of HBV in newborns is mainly caused by mothers infected with the HBV C genotype, and newborns whose mothers are infected with the HBV B genotype are the key population groups for intrauterine transmission of HBV. For pregnant women carrying the HBV C genotype, measures to prevent transmission should be strengthened. For pregnant women carrying HBV B genotype, HBV DNA testing and monitoring of hepatitis B vaccine response in their infants should be intensified. Pregnant women's "triple Ⅲ" status and HBV DNA are key risk factors for HBV intrauterine transmission.