A Phase 2/3 interventional study of Calcium carbonate in Uterine Contraction, Labor Complication and Labor Active Dilated Cm, sponsored by Arrowhead Regional Medical Center. Completed at 1 site in United States. Open to female participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2025-07-09.
Sponsored by Arrowhead Regional Medical Center · Phase 2/3, Interventional, and Treatment
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
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.
55 studies on the registry are indexed under Dystocia; 12 are open to participants now.
This study's enrollment of 89 is below the median of 200 across 42 interventional studies indexed under Dystocia.
Browse Dystocia studies →Arrowhead Regional Medical Center is the lead sponsor of 15 studies on the registry; 1 is open to participants now.
Compared within Dystocia, this study's primary condition as ClinicalTrials.gg classifies it; the registry's first condition term is Obstetric Labor Complications. The counts are of registry records indexed under each term, refreshed daily. How we classify →
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Received no medications but monitored for the duration of the study
2,000 mg PO calcium carbonate as a single dose
Drug: Calcium carbonate
2,000 mg PO calcium carbonate as a single dose
Also known as: TUMS
Contraction Frequency
Recording the number of contractions in a ten-minute period for 2 hours
Time frame: Two hours after receiving the study medication or, for control participants, two hours after enrollment.
Uterine contraction strength
Recording Montevideo units every 30 minutes for 2 hours
Time frame: Two hours after receiving the study medication or, for control participants, two hours after enrollment.
Peak strength
Recording the max pressure generated during a contraction using an intrauterine pressure catheter during the 2-hour study period
Time frame: Two hours after receiving the study medication or, for control participants, two hours after enrollment.
Duration of the first stage of labor
Record the length of the first stage of labor from 6 cm to 10 cm dilation
Time frame: Calculated at the time of delivery
Duration of the second stage of labor
Record the time from 10 cm to delivery of the baby
Time frame: Calculated at the time of delivery
Mode of delivery
Determine whether or not patient had a spontaneous vaginal bleeding, operative vaginal delivery, or cesarean delivery
Time frame: Calculated at the time of delivery
Pitocin dose
Record the maximum dose of Pitocin used during labor
Time frame: Calculated at the time of delivery
Postpartum hemorrhage
Determine which patients had a blood loss of greater than or equal to 1000 mL
Time frame: at the time of discharge (assessed up to 5 days)
Neonatal outcomes
Determine which babies were admitted to neonatal intensive care unit (NICU) and had a low 5- minute APGAR score
Time frame: at the time of discharge (assessed up to 5 days)
PDFs hosted by the registry, ClinicalTrials.gov.
Plan to share: Undecided — Study has already been completed, will analyze data first and then decide
Ran from Apr 2024 to primary completion in May 2025, 13 months.
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This study is completed, as verified in Jun 2025. You cannot join it, but the record below documents what was studied.
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Studies of the drug tested here: Calcium Carbonate
Arrowhead Regional Medical Center