# Reviewer C

## Comments

This multicentre, double blind, randomised phase 3 trial addresses an important and clinically relevant question: whether prophylactic tranexamic acid can reduce postpartum haemorrhage (PPH) in women with placenta praevia, a population at particularly high risk of severe bleeding. Given the global burden of PPH and the limited preventive options for high-risk caesarean deliveries, this study has clear potential to inform clinical guidelines and clinical decision-making.

### Major comments

- Page 9, lines 241–248: The primary outcome combines calculated estimated blood loss ≥1000 mL and red cell transfusion within 2 days. While pragmatic, these components reflect different clinical processes. Transfusion decisions may vary across centres despite similar blood loss. The authors are encouraged to clarify whether transfusion thresholds were standardised or audited across sites and to discuss the potential impact of inter-centre variability on the composite outcome.

- Page 11, lines 324–325; page 12, lines 295–296: Participants with missing postoperative haematocrit values were excluded from the primary analysis. Although the number is small, a brief justification for using complete-case analysis or a sensitivity analysis exploring plausible assumptions for missing values would strengthen methodological transparency.

- Page 16, lines 415–418: The authors appropriately note the single-country design as a limitation. This section could be strengthened by briefly comparing key characteristics of this cohort (e.g., BMI, prevalence of placenta accreta spectrum, surgical practices) with those commonly reported in non-Chinese settings to better contextualise international applicability.

### Minor comments

- Page 1 vs page 3: The title presented on the first page of the manuscript differs from the title used in the main text. This inconsistency should be corrected to ensure alignment across the submission.

- Page 3, lines 1–3: Consider explicitly indicating that tranexamic acid was used prophylactically to improve clarity and precision.

- Page 13–15: The discussion would benefit from explicitly referencing recent high-quality syntheses of the evidence, such as the updated systematic review and meta-analysis by Cheema et al. (2023), which demonstrated a reduction in blood loss and transfusion requirements after caesarean section with tranexamic acid. Integrating these findings would help situate the present trial within the broader literature and highlight how this study advances evidence specifically in a high-risk placenta praevia population.

- Ensure consistent use of either "praevia" or "previa" throughout the manuscript in line with journal style.