Analysis of 11 infants infected through mother-to-child transmission of hepatitis B virus

Objective To investigate the causes of HBV transmission in 11 infants, and to provide clinical evidence for further HBV reduction through mother-to-child transmission. Methods Total of 409 infants given birth by HBV positive mothers had been observed and tracked in Beijing Ditan Hospital, Capital Medical University from December 2010 to June 2012. All the infants were given HBV immunoglobulin (HBIG) 200 IU 2 hours after birth and 15 to 30 days after birth. Meanwhile, routine HBV vaccination (recombinant yeast hepatitis B vaccine 10 μg, 0-1-6 Scheme) was given to each infant. HBV serum markers and HBV DNA were tested at birth and followed up at 1st month, 7th month until 3 years old after birth. The 409 infants were divided into three groups according to the HBV levels of their mothers: HBV negative group (< 5 × 102 copies/ml, 147 cases), HBV DNA low level group (≥ 5 × 102 - < 1 × 106 copies/ml, 124 cases) and HBV DNA high level group (≥ 1 × 106 copies/ml, 138 cases). The feeding method, delivery mode, mother serum HBV DNA and HBeAg level were evaluated for the impact of mother-to-child transmission by Logistic regression analysis. Results There were 5 HBV positive infants who got positive HBV results from the first test (one month after birth), and kept positive in the subsequent follow-up. HBV DNA levels were higher than 1 × 106 copies/ml. The transmission was considered to be intrauterine infection. The other 6 infants got HBV negative results one month after birth, and HBsAb turned to be positive. But during the follow-up, 5 cases turned to be HBV positive at the 7th month after birth and one case turned positive at the 12th month after birth. The infection time implied postpartum infection. The mother-to-child transmission rates were 0, 0.81 % (1/124) and 7.25% (10/138) in HBV DNA negative group, HBV DNA low level group and HBV DNA high level group, respectively. The relative risk of HBV transmission was 8.98 times in high HBV DNA group compared with low HBV DNA group (P = 0.01). The result of Logistic regression analysis showed that HBV DNA level of mothers was the independent risk factor for mother-to-child transmission (95%CI: 1.28-6.39, P = 0.01). Conclusions Through strict active-passive combined immunization of HBV, there were still risks for HBV transmission from mother to child. Besides intrauterine infection, postpartum infection was also an important reason. Especially when the passive HBsAb disappeared, meanwhile the vaccine have not establish the effective immunity, the infants were still under the risk of HBV transmission. Key words: Hepatitis virus; Hepatitis B; Mother-to-child transmission; HBV immunoglobulin; Biological marker