Objective: To investigate the effect of high viral loads (HBV DNA concentration in blood > 2.0 copy/ml) on the vertical transmission of hepatitis B virus in mothers with HBV DNA positivity.
Method: Forty pregnant women with HBV DNA positivity were divided randomly, double-blindly into 2 groups: at 28 weeks of pregnancy, one group received oral lamivudine (100 mg/d) and the other received oral placebo. The serum HBV DNA loads were tested at 28 and 40 weeks' gestation in mothers, and serum HBV DNA,HBsAg, HBeAg and anti-HBs were examined in infants at 12 month follow up.
Result: Thirty-nine infants finished (one twins) the follow up, and 2 infants lost (5%). Among them 4 infants were confirmed to be HBV infection (10%, 4/39), 2 in the treatment group (10%, 2/20) and 2 in the control group (11%, 2/19) (P > 0.05). The serum HBV DNA levels of 40 weeks' gestation in the treatment group, compared with the levels of 28 weeks' gestation in the treatment group and 40 weeks' gestation in the control group, showed a significant decline (P < 0.01). The HBV DNA levels of the mothers whose infants were infected, were (3.1 +/- 3.4) copy/ml, (3.1 +/- 3.2) copy/ml during 28 and 40 weeks' gestation, and for mothers whose infants were non-infected, the levels were (3.4 +/- 2.2) copy/ml, (2.6 +/- 1. 5) copy/ml respectively (P > 0.05). The mean values of anti-HBs of 18 infants in the treatment group showed no significant difference as compared to 17 infants in the control group, (594 +/- 416) U/L vs (458 +/- 398) U/L (P > 0.05).
Conclusion: The pregnant women's HBV DNA loads could be obviously decreased from high viral loads (HBV DNA concentrations in blood > 2.0 copy/ml) after they take lamivudine from 36 weeks' gestation. But it might not reduce the maternal-fetal vertical transmission of HBV infection.