Efficacy and safety of tenofovir disoproxil fumarate in pregnancy to prevent perinatal transmission of hepatitis B virus

Background & Aims Perinatal transmission of hepatitis B virus still occurs despite immunoprophylaxis in approximately 9% of children from highly viraemic mothers. Antiviral therapy in this setting has been suggested, however with limited evidence to direct agent choice. Methods We conducted a multi-centre, prospective, opt-in observational study of antiviral safety and efficacy in pregnant women with high viral load (>7 log IU/ml); lamivudine was used from 2007 to 2010 and tenofovir disoproxil fumarate (TDF) from late 2010. Outcomes of treated and untreated cohorts were compared. Results 120 women with 130 pregnancies used TDF (58), lamivudine (52 including four who switched due to TDF intolerance) and no therapy (20). 96% were HBeAg positive, with baseline viral load mean 7.8 log IU/ml (±0.72) and ALT median 25 U/L (18.75–33). Duration of antiviral theraphy before birth was mean 58 days (±19) TDF and 53 (±14) lamivudine. Viral load declined by 3.64 log IU/ml (±0.9) TDF and 2.81 log IU/ml (±1.33) lamivudine. Virologic failure (birth viral load >7 IU/ml) occurred in 3% and 18% respectively. Congenital abnormality rate and neonatal growth centiles were similar across cohorts. Perinatal transmission reduced significantly to 2% and 0% in TDF and lamivudine cohorts, compared with 20% in untreated. Conclusions TDF in this setting is safe, effective and more potent than lamivudine. Antiviral therapy did not adversely impact obstetric or infant parameters. More TDF intolerance occurred than expected. Perinatal transmission was significantly reduced in antiviral therapy cohorts.