Can a simple calcium tablet help prevent postpartum bleeding?
NCT ID NCT06650930
First seen Aug 12, 2026 · Last updated Aug 13, 2026 · Updated 1 time
Summary
This study looks at how quickly and effectively oral calcium is absorbed into the blood of pregnant women during labor. Participants receive a single dose of calcium carbonate (like Tums) or calcium citrate, and blood calcium levels are tracked over four hours. The goal is to understand whether oral calcium could be a practical way to raise blood calcium quickly, which might help prevent postpartum hemorrhage—excessive bleeding after delivery.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- Active substance
- oral calcium carbonate (and calcium citrate)
- What this could lead to
- If this works, it could guide the use of oral calcium to help prevent postpartum hemorrhage, a serious complication after childbirth.
- What could go wrong
- This is a very early, small study focused on how calcium is absorbed, not on whether it prevents bleeding. Results may not translate into clinical benefit.
This is an AI summary of the original study and may miss details. Read our disclaimer.
Study facts
What this study's own registry entry says, in plain language.
- Phase
-
Early phase 1
The earliest testing in people: a first look at safety, in a very small group.
- Participants
-
20 people
The number who actually took part.
- Started
-
Jan 2025
- Finished
-
Dec 2025
- Lead sponsor
-
Other sponsor
The registry's catch-all category, for sponsors it does not file as a company, a government agency, or a research network.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
- Ages
-
18 to 45 years
- Sex
-
Female participants only
- Healthy volunteers
-
Not accepted
This study is not open to healthy volunteers. The entry requirements below say who it is open to.
Show the full entry requirements Hide the full entry requirements
Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
Inclusion Criteria: * Pregnant female subjects at the study institution, admitted for labor (spontaneous, augmented, or induced) Exclusion Criteria: 1. severe range blood pressure (BP \>160/\>110) within the 48 hours prior to delivery 2. patient age \<18 years or \>45 years 3. renal dysfunction with a documented serum Cr \> 1.0 mg/dL 4. known history of congenital or acquired cardiac disease or history of arrhythmia 5. patient taking digoxin 6. patient currently taking a calcium channel blocker 7. Weight \<55kg or \>100kg, or 8. receiving magnesium infusion within 24 hours prior to or during cesarean delivery 9. Prior or planned administration of calcium by the obstetric or anesthesiology teams for clinical indications within 24 hours of study enrollment 10. Patient took a calcium supplement in the past 48 hours 11. Patient status is NPO (nothing by mouth) as ordered by the clinical team
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Conditions
The condition(s) this trial relates to.
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
Contacts and locations
Locations
-
Stanford Children's Health, Lucile Packard Children's Hospital
Stanford, California, 94305, United States
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Other studies related to the condition(s) this trial covers.
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