Abstract: Objective To understand the rate of hepatitis B virus e antigen (HBeAg) seroconversion in chronic hepatitis B virus (HBV)-infected pregnant women in the immune-tolerant phase and receive nucleos(t)ide analogues (NAs) therapy in mid-pregnancy and continue NAs therapy after delivery,and to explore independent factors influencing HBeAg seroconversion. ^Method This was a case-control study that included 161 pregnant women with chronic HBV infection who were HBeAg positive, had an alanine aminotransferase (ALT) less than twice the upper limit of normal during pregnancy, were treated with NAs in mid-pregnancy, and continued NAs after delivery in The First Affiliated Hospital of Xi'an Jiaotong University and the 301 Hospital between January 2014 and December 2020. They were divided into a conversion group and a non-conversion group according to whether they had or had not occurred HBeAg seroconversion in the postpartum period, and the independent influencing factors of HBeAg seroconversion were analyzed using univariate analysis and multivariate logistic regression model. Result 27.95% of chronically HBV-infected pregnant women had HBeAg seroconversion within 96 weeks postpartum. The levels of baseline ALT and aspartate aminotransferase (AST) in the conversion group were significantly higher than those in the non-conversion group (P<0.05). The titers of HBeAg were significantly lower than those in the non-conversion group (P<0.05), and the reductions and reduction rates of HBeAg and hepatitis B virus DNA(HBV DNA) in the conversion group from the second trimester to the prenatal period were higher than those in the non-conversion group (P<0.05). Univariate and multivariate logistic regression analysis showed that the rate of decline in hepatitis B virus DNA(HBV DNA) from mid-pregnancy to prenatal period (OR=1.035,95%CI：1.005-1.065,P=0.023) and the rate of decline in HBeAg(OR=1.056,95%CI：1.025-1.087,P<0.001) were the independent influencing factors for the occurrence of HBeAg seroconversion postpartum. Conclusion HBeAg-positive pregnant women with chronic HBV who are given NAs treatment antiviral therapy from mid-pregnancy to after delivery are more likely to develop HBeAg seroconversion. The greater the decrease in HBV DNA load and HBeAg titer from mid-pregnancy to prenatal period, he higher the likelihood of HBeAg seroconversion with continuous postpartum NA therapy, which provides a valuable reference for clinicians in evaluating the postpartum condition of chronic HBV-infected pregnant women and developing management strategies.

Key words: Hepatitis B virus e antigen, Hepatitis B virus, Hepatitis B virus DNA, Mother to child transmission, Nucleoside (acid) analogues, Influencing factor