Oral Calcium Supplementation in Labor

Not Applicable

Completed

• Conditions: Uterine Contraction; Labor Complication; Labor Dystocia; Labor Active Dilated Cm; Labor Duration; Labor; Labor Delivery
• Interventions: Drug: Calcium carbonate

• Registration Number: NCT07056062
• Lead Sponsor: Arrowhead Regional Medical Center

Brief Summary

The goal of this clinical trial is to learn if oral calcium carbonate can improve uterine contractions and labor outcomes in term pregnancies. It will also evaluate the safety of calcium carbonate when used during labor. The main questions it aims to answer are:

Does oral calcium carbonate increase uterine contraction strength? Does it lead to shorter labor duration or higher vaginal delivery rates? What side effects or complications, if any, occur with calcium carbonate use during labor?

Researchers will compare oral calcium carbonate to no treatment to see if it helps improve labor efficiency and reduce cesarean delivery rates.

Participants will:

Be randomly assigned to receive either 2,000 mg of oral calcium carbonate or no intervention Undergo monitoring with an intrauterine pressure catheter to measure contraction strength Be observed for two hours without oxytocin to assess calcium's direct effect on contractions Have data collected on labor progression, delivery outcomes, and neonatal health

Detailed Description

In the United States, nearly one-third of deliveries are performed via cesarean section, with labor dystocia remaining a leading indication. Labor dystocia may result from a variety of maternal and fetal factors, including malposition, cephalopelvic disproportion, or ineffective uterine contractions. When contractions are inadequate, the standard intervention is intravenous oxytocin. However, prolonged or high-dose oxytocin administration can lead to receptor desensitization, reducing its effectiveness and increasing the risk of postpartum hemorrhage.

Calcium plays a key role in myometrial contractility by facilitating calcium influx through L-type channels in myometrial cells, which triggers intracellular calcium release and action potentials. During labor, upregulation of calcium channels enhances the uterus's responsiveness to contractile stimuli. Elevated serum calcium levels have been associated with stronger and more effective contractions.

Adjunctive intravenous calcium administration with oxytocin has been shown to improve labor outcomes, including higher rates of vaginal delivery within 24 hours of induction and reduce blood loss in cesarean deliveries. However, the potential role of oral calcium supplementation in enhancing labor progression has not been evaluated in clinical trials. Given its physiological relevance, accessibility, and low-risk profile, oral calcium may represent a simple adjunct to improve labor efficiency and reduce cesarean rates.

This study aims to evaluate the impact of oral calcium carbonate supplementation during labor on uterine contractility and clinical outcomes. The investigators hypothesize that calcium carbonate administered intrapartum will enhance uterine contractions, resulting in higher vaginal delivery rates, shorter time to delivery, and reduced blood loss.

Study Timeline

• Study Start: 2024-04-30
• Primary Completion: 2025-05-30
• Study Completion: 2025-05-30
• Status Verified: 2025-06
• Study First Submitted: 2025-06-21
• Study First Submitted QC: 2025-06-28
• Last Update Submitted: 2025-06-28
• Study First Posted: 2025-07-09
• Last Update Posted: 2025-07-09

Recruitment & Eligibility

• Status: COMPLETED
• Sex: Female
• Target Recruitment: 89

Inclusion Criteria

• Had an intrauterine pressure catheter in place
• Term gestation, greater than or equal to 37 weeks of gestation
• Singleton pregnancy
• Cephalic presentation
• > 18 years of age

Exclusion Criteria

• incarceration
• multiple gestation
• active illicit drug use
• abnormal clinical pelvimetry
• Suspected fetal macrosomia defined as estimated fetal weight ≥4250 grams
• intrauterine growth restriction
• abnormal placentation
• prior cesarean delivery
• maternal history of arrhythmia
• hyperparathyroidism
• heart failure
• renal or hepatic failure
• nephrolithiasis
• receipt of medications known to affect uterine contractility-such as magnesium sulfate, terbutaline, or recent misoprostol in the last four hours

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Calcium carbonate	Calcium carbonate	2,000 mg PO calcium carbonate as a single dose

Primary Outcome Measures

Name	Time	Method
Contraction Frequency	Two hours after receiving the study medication or, for control participants, two hours after enrollment.	Recording the number of contractions in a ten-minute period for 2 hours
Uterine contraction strength	Two hours after receiving the study medication or, for control participants, two hours after enrollment.	Recording Montevideo units every 30 minutes for 2 hours
Peak strength	Two hours after receiving the study medication or, for control participants, two hours after enrollment.	Recording the max pressure generated during a contraction using an intrauterine pressure catheter during the 2-hour study period

Secondary Outcome Measures

Name	Time	Method
Mode of delivery	Calculated at the time of delivery	Determine whether or not patient had a spontaneous vaginal bleeding, operative vaginal delivery, or cesarean delivery
Duration of the first stage of labor	Calculated at the time of delivery	Record the length of the first stage of labor from 6 cm to 10 cm dilation
Duration of the second stage of labor	Calculated at the time of delivery	Record the time from 10 cm to delivery of the baby
Pitocin dose	Calculated at the time of delivery	Record the maximum dose of Pitocin used during labor
Neonatal outcomes	at the time of discharge (assessed up to 5 days)	Determine which babies were admitted to neonatal intensive care unit (NICU) and had a low 5- minute APGAR score
Postpartum hemorrhage	at the time of discharge (assessed up to 5 days)	Determine which patients had a blood loss of greater than or equal to 1000 mL

Trial Locations

Locations (1)

Arrowhead Regional Medical Center; 🇺🇸 Colton, California, United States