Calcium Gluconate for Reduced Blood Loss During Vaginal Delivery

Postpartum hemorrhage (PPH) remains a major cause of maternal morbidity worldwide. In addition to clinically recognized PPH, a substantial proportion of women experience significant postpartum hemoglobin decline without overt signs of excessive bleeding. Such blood loss may contribute to postpartum anemia, fatigue, delayed recovery, and increased healthcare utilization. Calcium plays a critical role in both uterine muscle contraction and the coagulation cascade. Transient reductions in serum calcium concentrations have been observed during labor and immediately after delivery. It has been hypothesized that calcium supplementation during the third stage of labor may enhance uterine contractility and reduce postpartum blood loss. The objective of this randomized, double-blind, placebo-controlled trial is to evaluate whether intravenous calcium gluconate administered immediately after umbilical cord clamping reduces postpartum blood loss following vaginal delivery. Eligible participants will be randomized in a 1:1 ratio to receive either 10 mL of 10% calcium gluconate diluted in 100 mL of normal saline or 110 mL of normal saline placebo administered intravenously immediately after umbilical cord clamping. Participants, healthcare providers, and outcome assessors will remain blinded to treatment allocation. The co-primary outcomes are: (1) the proportion of participants experiencing a hemoglobin decrease of at least 2 g/dL from the pre-delivery value to the lowest postpartum hemoglobin value recorded during hospitalization, and (2) the mean change in hemoglobin level from the pre-delivery value to the lowest postpartum hemoglobin value recorded during hospitalization. Secondary outcomes include clinically diagnosed postpartum hemorrhage, need for additional uterotonic medications, blood transfusion, intravenous iron administration, length of hospital stay, and composite maternal morbidity outcomes. The findings of this study may provide evidence regarding the effectiveness and safety of calcium gluconate as a simple and inexpensive intervention for reducing postpartum blood loss after vaginal delivery.