Julia Romina M Boers, Mirely Garcia, Fabrizio Zullo, Christian J Miller, Moeun Son
Peri-delivery calcium administration was associated with reduced postpartum blood loss and decreased need for additional uterotonics. Although effect sizes were modest and evidence was limited by few studies and heterogeneity in calcium formulations and doses, these findings suggest that calcium may enhance uterine contractility. Larger RCTs are needed to confirm efficacy and to determine optimal dosing.
OBJECTIVE: To examine whether peri-delivery administration of exogenous calcium improves postpartum bleeding outcomes.
DATA SOURCES: We conducted a systematic review of randomized controlled trials (RCTs) and quasi-randomized trials comparing pregnant individuals undergoing vaginal or cesarean delivery who received exogenous calcium before or within 1 hour of delivery with those who received no calcium supplementation. We searched Ovid MEDLINE, Ovid EMBASE, CINAHL, Scopus, Web of Science, and CENTRAL/The Cochrane Library (including ClinicalTrials.gov) from inception through July 10, 2025 (PROSPERO 2025 CRD420251091214).
METHODS OF STUDY SELECTION: Titles, abstracts, and full texts were independently screened in duplicate. Six RCTs and one quasi-randomized study including 806 participants (403 intervention, 403 control) were included. All participants underwent cesarean delivery. Interventions included intravenous calcium chloride or calcium gluconate, administered after delivery, after cord clamping, or perioperatively.
TABULATION INTEGRATION AND RESULTS: The primary outcome was estimated or quantitative postpartum blood loss. Secondary outcomes included the use of additional uterotonics beyond prophylactic oxytocin and other postpartum bleeding-related outcomes. Random-effects models were used to calculate ratio of means, pooled mean differences, and risk ratios (RRs) with 95% CIs. Calcium supplementation was associated with 8% lower postpartum blood loss compared with control (ratio of means 0.92, 95% CI, 0.88-0.97). Calcium supplementation was associated with a lower frequency of additional uterotonic use (27.1%) compared with controls (41.9%) (RR 0.69, 95% CI, 0.49-0.96). Low-to-moderate heterogeneity was observed, and most studies were judged to be at low risk of bias.
CONCLUSION: Peri-delivery calcium administration was associated with reduced postpartum blood loss and decreased need for additional uterotonics. Although effect sizes were modest and evidence was limited by few studies and heterogeneity in calcium formulations and doses, these findings suggest that calcium may enhance uterine contractility. Larger RCTs are needed to confirm efficacy and to determine optimal dosing.
SYSTEMATIC REVIEW REGISTRATION: PROSPERO, CRD420251091214.