To investigate the clinical efficacy of tenofovir disoproxil (TDF) on blocking mother-to-child tranmission of hepatitis B virus (HBV) in middle pregnant women with high HBV load of different genotypes in Sichuan region.

Total of 258 pregnant cases of hepatitis B with high HBV load were selected from the Public Health Clinical Center of Chengdu from August 2016 to August 2019, and divided into observation group (156 cases) and control group (102 cases) according to their willingness. The patients in observation group were orally given TDF from 24 gestational weeks until delivery, while patients in control group did not receive antiviral therapy. The infants in both groups were given standardized immunizations to hepatitis B. The safety of pregnant women and infants and the effect of mother-to-child blocking after antiviral therapy were analyzed.

There were 213 cases (82.5%) of HBV genotype B and 45 cases (17.5%) of HBV genotype C among the 258 pregnant women, with significant difference (χ² = 14.616, P < 0.001). No B/C hybrid genotype and other genotype were detected. HBV DNA baseline between genotype B and genotype C were not statistically significant (t = 0.752, P = 0.458). There were no differences between the two groups on preterm birth rate of patients in newborns (χ² = 0.018, P = 0.904), the rate of caesarean section (χ² = 0.038, P = 0.813) and the amount of bleeding in 24 hours after birth (t = 0.153, P = 0.703). HBV DNA levels decreased significantly of patients in observation group during delivery than before antiviral treatment (t = 19.678, P = 0.032). Follow-up to 7 months after delivery, two infants in observation group were detected HBsAg positive (with the positive rate of 1.28%), while HBeAg and HBV DNA were both negative. Nine infants in the control group were detected HBsAg positive (with the positive rate of 8.82%), among whom, 6 cases were detected HBeAg positive (with the positive rate of 5.88%) and 6 cases HBV DNA positive (with the positive rate of 5.88%). The positive rates of HBsAg between two groups of infants were statistically significant (χ² = 4.956, P = 0.038). HBV DNA load after antiviral therapy of HBV genotype B and C infected cases in observation group were significantly reduced, with no significant difference (t = 1.043, P = 0.491). Among the 11 patients with mother-to-child transmission, 8 were genotype B and 3 were genotype C, and the difference of mother-to-child transmission between the two genotypes was statistically significant (χ² = 4.527, P = 0.045). In observation group, 3 pregnant women experienced mild dizziness and fatigue, 1 case with mild nausea and decreased appetite, the incidence of adverse reaction was 2.6% (4/156). No serum phosphorus and blood creatinine abnormalities occurred during the treatment. The differences between head circumference, length and body mass of newborns in both groups were not statistically significant (all P > 0.05).

HBV genotype of pregnant women with hepatitis B in Sichuan region was mainly genotype B, and the safty of TDF administrated to middle pregnant women with high HBV load and different genotypes was good, also mother-to-child tranmission of hepatitis B virus could be effectively blocked.