Association between shock index and postpartum hemoglobin level and blood transfusion requirement in women delivering at public hospitals in Shiraz, 2023–2024

BACKGROUND: Postpartum hemorrhage is a leading cause of maternal morbidity and mortality worldwide, affecting over 14 million women annually and causing approximately 80,000 preventable deaths.The Shock Index (SI), calculated as the ratio of heart rate to systolic blood pressure, is a simple, non-invasive tool for detecting early hemodynamic instability. Despite its potential clinical usefulness, few studies have examined the association between SI, postpartum hemoglobin levels, and blood transfusion requirements. This study evaluated the association between SI and these outcomes among women delivering in public hospitals in Shiraz, Iran, during 2023-2024. METHODS: This retrospective cross-sectional study analyzed data from 370 women who delivered between 2023 and 2024 at three tertiary hospitals in Shiraz. Inclusion criteria included Iranian nationality, age > 18 years, delivery at or beyond 22 weeks' gestation (regardless of neonatal status), and no comorbidities(e.g., pre-eclampsia, gestational hypertension, diabetes, or thyroid disorders). The SI was calculated at the fourth 15-minute interval post-delivery and categorized as low (< 0.70), moderate (0.70-0.89), or high (≥ 0.90). Demographic and clinical data, pre- and postpartum hemoglobin levels, and transfusion status were extracted from medical records. Analyses were performed using chi-square and two-way ANOVA tests in SPSS version 22. RESULTS: Among the 370 women included in the study, 42 required blood transfusion. In analyses stratified by delivery type (vaginal with or without episiotomy and cesarean section), categorized SI was not significantly associated with postpartum hemoglobin decline or transfusion requirement (P > 0.05). However, in simple group comparisons, women who required transfusion had significantly higher mean heart rates (88.1 ± 17.8 vs. 81.9 ± 12.4 beats/min), lower systolic blood pressure (108.6 ± 7.1 vs. 114.8 ± 8.1 mmHg), and higher SI values (0.81 ± 0.18 vs. 0.72 ± 0.11) compared with the non‑transfusion group (P < 0.001). CONCLUSION: This study found that women who required blood transfusion had higher heart rates, lower systolic blood pressure, and higher SI than those who did not. However, no significant associations were observed between categorized SI and postpartum hemoglobin levels or transfusion requirement within delivery-type subgroups. Because this study evaluated associations only and did not assess diagnostic accuracy, the SI cannot be considered a screening tool based on these findings. Further prospective studies with larger sample sizes and standardized data collection are needed to evaluate the diagnostic performance of the SI and clarify its potential role in the early identification of postpartum hemorrhage.