[Effects related to HBeAg status and mode of delivery as well as the interactions on intrauterine transmission among HBsAg-positive mothers].

OBJECTIVE: To investigate the relationship between HBeAg status, mode of delivery and intrauterine transmission of the HBsAg-positive mothers as well as their interactions.

METHODS: A total of 344 HBsAg-positive pregnant women and their infants were enrolled in this study. The mothers were recruited from the Third People's Hospital of Taiyuan, from July 2011 to January 2013. Serum HBV-M and HBV DNA were measured using the electro-chemiluminescence immune-assay (ECLIA) kits and fluorescene quantitative polymerase chain reaction (FQ-PCR) assay, respectively. Univariate analysis and unconditional logistic regression analysis were used to explore the risk factors on intrauterine transmission.

RESULTS: Among 344 neonates born to HBsAg-positive mothers, 42 were validated as HBV intrauterine transmitted, with the rate of intrauterine transmission as 12.21% (42/344). The rates of intrauterine transmission among HBeAg-positive and HBeAg-negative mothers were 18.52% (30/162) and 6.59% (12/182), respectively. The rates of intrauterine transmission were 22.22% (34/153) and 4.19% (8/191) in the groups of vaginal birth or caesarean delivery, respectively. RESULTS from unconditional logistic regression analysis showed that after adjusting the confounding factors, HBeAg-positive mothers (OR=3.003, 95% CI: 1.368-6.593) and vaginal birth (OR=7.333, 95% CI: 3.108-17.302) might serve as the risk factors for the HBV intrauterine transmission. Data from the interaction analysis showed that there were additive interactions [relative excess risk due to interaction (RERI) as 14.229; the attributable proportion (AP) due to interaction as 0.587; the synergy index (SI) as 2.579] and multiplicative interaction (OR=1.084, 95%CI: 0.720-1.632) between HBeAg status and the modes of delivery.

CONCLUSION: Vaginal birth and HBeAg-positive might serve as the risk factors for HBV intrauterine transmission. There also appeared additive interactions between HBeAg status and the mode of delivery.