Tenofovir alafenamide or tenofovir disoproxil fumarate in pregnancy to prevent HBV transmission: Maternal ALT trajectory and infant outcomes

Abstract Background The use of antiviral agents, specifically tenofovir disoproxil fumarate (TDF), in pregnant women to prevent mother‐to‐child HBV transmission is a key step towards hepatitis elimination. However, data on using tenofovir alafenamide (TAF) is insufficient. The frequent occurrence of postpartum ALT flares may impact the clinical implementation. Methods The maternal and infant outcomes were compared in multi‐centre trials of high viral load HBsAg/HBeAg+ pregnant women receiving TAF or TDF from the third trimester until 2 weeks postpartum with intensive follow‐ups. To explore the dynamic pre‐ and postpartum changes in ALT levels, we used a group‐based trajectory model for analysing data of 332 women from three prospective studies. Results After treatment, the maternal HBV DNA levels significantly decreased from baseline to delivery: 7.87 ± 0.59 to 3.99 ± 1.07 Log 10 IU/mL TAF ( n = 78) and 8.30 ± 0.36 to 4.47 ± 0.86 Log 10 IU/mL (TDF, n = 53), with viral load reductions of 3.87 versus 3.83 Log 10 IU/mL. The HBsAg‐positive rates among 12‐month‐old infants were 1.28% (1/78) versus 1.82% (1/55) respectively ( p = 1.00). Of the TAF or TDF‐treated mothers, 25.64% versus 16.98% experienced ALT > 2X ULN, and 11.54% versus 1.89% received extended antiviral treatment. Our model revealed four distinct ALT patterns: stable ALT (87.2%), moderate (8.0%) or marked (2.4%) postpartum flares, or prepartum elevations (2.4%). Conclusions TAF effectively reduces mother‐to‐child HBV transmission, but prophylaxis failure still occurred in few cases. Postpartum ALT flares are common in women receiving TAF or TDF during pregnancy. Approximately 12.8% of mothers may require extended postpartum antiviral treatment. Clinical trial number: NCT03695029 (ClinicalTrials.gov).