Background <p>To investigate the impact of tenofovir disoproxil fumarate (TDF) withdrawal timing on elevated postpartum alanine aminotransferase (ALT) levels and breastfeeding in pregnant women who received TDF therapy to prevent mother-to-child transmission (MTCT) of hepatitis B virus (HBV) infection.</p> Methods <p>All enrolled women began treatment with TDF during weeks 24–32 of pregnancy and were divided into three groups that stopped TDF at delivery (Group A), at 4 weeks postpartum (Group B), or at 12 weeks postpartum (Group C). The biochemical and virological markers of hepatitis B were regularly measured and compared. Binary logistic regression analysis was used to explore the risk factors of elevated ALT levels.</p> Results <p>Elevated postpartum ALT levels were observed in 91 of the 160 patients, including 38 out of 59 (64.41%) in Group A, 27 out of 51 (52.94%) in Group B, and 26 out of 50 (54%) in Group C. The incidence of elevated ALT levels did not differ significantly among the three groups (<i>P</i> = 0.338). Moreover, there was no significant difference in the severity of elevated ALT levels among the three groups (<i>P</i> = 0.558). Binary logistic regression analysis showed that ALT at delivery was an independent risk factor for elevated ALT levels (odds ratio = 1.098, 95% confidence interval, 1.039–1.160, <i>P</i> = 0.001). ROC analysis identified ALT ≥ 23 U/L at delivery as the optimal cutoff (AUC = 0.703, 95% CI: 0.622–0.785) for predicting elevated postpartum ALT levels. Breastfeeding rates were significantly higher in Group A (79.66%) compared to Group B (25.49%) and Group C (42%), both <i>P</i> values = 0.000.</p> Conclusions <p>When TDF is used to prevent MTCT of HBV, withdrawal timing did not significantly affect overall ALT elevation patterns. However, early TDF withdrawal at delivery was associated with higher breastfeeding rates, and mothers with ALT levels ≥ 23 U/L at delivery may benefit from extended postpartum antiviral therapy.</p> Graphical Abstract <p></p>