Oral Calcium Supplementation in Labor

NCT07056062 | Completed Phase 2 FDA Drug

• 1 other identifier: 24-16
• Study Type: interventional
• Target: 89
• Locations: 1 country
• Sites: 1

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

Conditions

Uterine Contraction; Labor Complication; Labor Active Dilated Cm; Labor Dystocia; Labor Duration; Labor; Labor Delivery

Keywords

calcium carbonate; labor; vaginal delivery; cesarean delivery

Outcome Measures

Primary Outcomes (3)

• Contraction Frequency

  Recording the number of contractions in a ten-minute period for 2 hours

  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

  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

  Two hours after receiving the study medication or, for control participants, two hours after enrollment.

Secondary Outcomes (6)

• Duration of the first stage of labor

  Calculated at the time of delivery

• Duration of the second stage of labor

  Calculated at the time of delivery

• Mode of delivery

  Calculated at the time of delivery

• Pitocin dose

  Calculated at the time of delivery

• Postpartum hemorrhage

  at the time of discharge (assessed up to 5 days)

Study Arms (2)

Standard of care

NO INTERVENTION

Received no medications but monitored for the duration of the study

Calcium carbonate

EXPERIMENTAL

2,000 mg PO calcium carbonate as a single dose

Drug: Calcium carbonate

Interventions

Calcium carbonate DRUG

2,000 mg PO calcium carbonate as a single dose

Also known as: TUMS

Calcium carbonate

Eligibility Criteria

• Age: 18 Years+
• Sex: female
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• 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

You may not qualify if:

• 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

Sponsors & Collaborators

• Arrowhead Regional Medical Center: lead

Study Sites (1)

Arrowhead Regional Medical Center

Colton, California, 92324, United States

Location

Related Publications (6)

• Cai R, Chen L, Xing Y, Deng Y, Li J, Guo F, Liu L, Xie C, Yang J. RETRACTED: Oxytocin with calcium vs oxytocin for induction of labor in women with term premature rupture of membranes: a randomized controlled trial. Am J Obstet Gynecol MFM. 2024 Nov;6(11):101502. doi: 10.1016/j.ajogmf.2024.101502. Epub 2024 Sep 20.

  PMID: 39307241 BACKGROUND

• Ansari JR, Yarmosh A, Michel G, Lyell D, Hedlin H, Cornfield DN, Carvalho B, Bateman BT. Intravenous Calcium to Decrease Blood Loss During Intrapartum Cesarean Delivery: A Randomized Controlled Trial. Obstet Gynecol. 2024 Jan 1;143(1):104-112. doi: 10.1097/AOG.0000000000005441. Epub 2023 Nov 3.

  PMID: 37917943 BACKGROUND

• Papandreou L, Chasiotis G, Seferiadis K, Thanasoulias NC, Dousias V, Tsanadis G, Stefos T. Calcium levels during the initiation of labor. Eur J Obstet Gynecol Reprod Biol. 2004 Jul 15;115(1):17-22. doi: 10.1016/j.ejogrb.2003.11.032.

  PMID: 15223159 BACKGROUND

• Pehlivanoglu B, Bayrak S, Dogan M. A close look at the contraction and relaxation of the myometrium; the role of calcium. J Turk Ger Gynecol Assoc. 2013 Dec 1;14(4):230-4. doi: 10.5152/jtgga.2013.67763. eCollection 2013.

  PMID: 24592112 BACKGROUND

• Wray S, Jones K, Kupittayanant S, Li Y, Matthew A, Monir-Bishty E, Noble K, Pierce SJ, Quenby S, Shmygol AV. Calcium signaling and uterine contractility. J Soc Gynecol Investig. 2003 Jul;10(5):252-64. doi: 10.1016/s1071-5576(03)00089-3.

  PMID: 12853086 BACKGROUND

• Obstetric care consensus no. 1: safe prevention of the primary cesarean delivery. Obstet Gynecol. 2014 Mar;123(3):693-711. doi: 10.1097/01.AOG.0000444441.04111.1d.

  PMID: 24553167 BACKGROUND

Related Links

• Related Info
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MeSH Terms

Conditions

Obstetric Labor Complications; Dystocia

Interventions

Calcium Carbonate

Condition Hierarchy (Ancestors)

Pregnancy Complications; Female Urogenital Diseases and Pregnancy Complications; Urogenital Diseases

Intervention Hierarchy (Ancestors)

Calcium Compounds; Inorganic Chemicals; Carbonates; Carbonic Acid; Carbon Compounds, Inorganic; Minerals

Study Officials

• Guillermo Valenzuela, MD

  Arrowhead Regional Medical Center

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: phase 2
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: MFM Fellow

Model Details: Participants in the intervention group received a single oral dose of 2,000 mg calcium carbonate, consisting of four over-the-counter antacid tablets. This dose is well below the recommended daily maximum of 8,000 mg. The control group received no medication. Common side effects of calcium carbonate include constipation, bloating, and abdominal discomfort, while serious side effects such as hypercalcemia are rare.

Study Record Dates

• First Submitted: June 21, 2025
• First Posted: July 9, 2025
• Study Start: April 30, 2024
• Primary Completion: May 30, 2025
• Study Completion: May 30, 2025
• Last Updated: July 9, 2025

Record last verified: 2025-06

Locations

US (1)