Third trimester antiviral initiation may reduce mother-to-child HBV transmission
Mother-to-child transmission (MTCT) of the hepatitis B virus (HBV) from carrier mothers to their infants may be preventable if antiviral therapy is initiated from the third trimester of pregnancy, according to a study presented at RCOG 2018.
“Antiviral treatment in HBV carrier mothers from as early as 28–30 weeks gestation efficiently interrupts MTCT as indicated by infant serum HBsAg or HBV DNA,” said Dr Jyoti Ramesh Chandran from the Institute of Maternal and Child Health, Kozhikode, Kerala, India, who presented the findings.
Sixty HBsAg positive (and HBeAg positive) pregnant women aged 18–43 years at 20–34 weeks gestation with a viral load (HBV DNA) of >106 copies/mL were randomized to receive daily doses of lamivudine 100 mg (n=31) or tenofovir disoproxil fumarate (TDF) 300 mg (n=21) from the third trimester of pregnancy and continued for 1 month postpartum.
Women who were HBsAg positive but HBeAg negative, those with concurrent HIV or hepatitis C infections, and those with a history of renal or liver dysfunction were excluded.
Liver function tests were conducted in the mothers at diagnosis and at 3 and 6 months postpartum, while infant HBsAg, HBeAg, AST, ALT, and anti-HB levels were tested at 1 year. The infants were given hepatitis B immunoglobulin (200 IU) within 16 hours of birth and the HBV vaccine (10 µg) at 0, 1, and 6 months.
MTCT was defined in this study as infants with serum HBV DNA >20 IU/mL (above the lower limit of detection) or HBsAg positive at 12 months.
At 1 year, 23.3 percent of infants were HBsAg positive.
Earlier initiation of antiviral therapy significantly reduced HBV incidence in infants, where infants whose mothers initiated antiviral therapy at 31–34 weeks gestation were less likely to have HBV compared with those whose mothers initiated therapy at >34 weeks gestation (28.1 percent vs 83.3 percent; p=0.003), with no incidence of HBV in infants whose mothers initiated antiviral therapy before 30 weeks gestation. [RCOG 2018, abstract 6006]
Infants whose mothers had been given TDF were less likely to be HBsAg positive at 1 year than those whose mothers received lamivudine (6.9 percent vs 38.7 percent; p=0.004).
The incidence of side effects was comparable between patients on lamivudine and TDF (p=0.715). There was no incidence of HBV flare at 3 and 6 months following antiviral therapy cessation.
According to Chandran, while maternal screening and active and passive immunization have reduced the incidence of HBV perinatal transmission, prophylaxis cannot prevent intrauterine transmission of HBV from pregnant women to their infants. [Liver Int 2013;33 Suppl 1:188-194]
Thus, the trial was conducted to assess if antiviral therapy during the third trimester of pregnancy in high-risk women with chronic HBV infection could not only reduce the viral load in the women but also prevent perinatal transmission of the virus.
HBV vaccination status in the pregnant women could not be confirmed and HBV viral load was not tested after drug initiation and postpartum, both of which were study limitations, said Chandran, who called for large, well-designed, randomized, double-blind clinical trials to establish these findings.