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Oral Calcium in Pregnant Women With Hypertension

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00000543
Recruitment Status : Completed
First Posted : October 28, 1999
Last Update Posted : May 13, 2016
Information provided by:
National Heart, Lung, and Blood Institute (NHLBI)

Brief Summary:
To determine of providing calcium supplementation to women with pre-existing hypertension reduces the level of blood pressure, requirement for antihypertensive drugs, and incidence of pre-eclampsia.

Condition or disease Intervention/treatment Phase
Cardiovascular Diseases Heart Diseases Hypertension Pre-Eclampsia Pregnancy Toxemias Vascular Diseases Behavioral: dietary supplements Drug: calcium Phase 2

Detailed Description:


Maternal and fetal complications are more likely to occur in pregnant women with preexisting hypertension. Alterations in calcium metabolism, the renin angiotensin system, and intracellular free calcium concentration have been identified in this high risk population. The beneficial effects of calcium supplementation on blood pressure and the incidence of superimposed pre-eclampsia may be due to correction of the hormonal and cellular basis for vasoconstriction. The trial sought to prove that oral calcium lowered parathyroid hormone, reduced intracellular free calcium, and decreased vascular endothelin production, resulting in vasodilation and compensatory stimulation of the renin-angiotensin system.


Randomized. Double blind. In this observational study, subjects were assigned to two grams of supplemental elemental calcium or to placebo at 13 to 15 weeks gestation. The trial determined the effect of oral calcium supplementation on: the level of blood pressure; the need for antihypertensive drugs; forearm and peripheral vascular resistance; the incidence of maternal complications, including pre-eclampsia and eclampsia; and plasma levels of vitamin D3, ionized calcium, parathyroid, renin activity, angiotensin II, endothelin, nitrate/nitrite, prostacyclins, and intracellular calcium concentrations in lymphocytes and platelets. These variables were measured prior to randomization and every two months throughout pregnancy and the postpartum. Support ended in July 1999.

The study completion date listed in this record was obtained from the "End Date" entered in the Protocol Registration and Results System (PRS) record.

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Study Type : Interventional  (Clinical Trial)
Allocation: Randomized
Masking: Double
Primary Purpose: Prevention
Study Start Date : August 1993
Actual Study Completion Date : July 1999

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Calcium

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 40 Years   (Adult)
Sexes Eligible for Study:   Female
Accepts Healthy Volunteers:   No
Pregnant women with chronic hypertension.

Layout table for additonal information Identifier: NCT00000543     History of Changes
Other Study ID Numbers: 86
R01HL048846 ( U.S. NIH Grant/Contract )
First Posted: October 28, 1999    Key Record Dates
Last Update Posted: May 13, 2016
Last Verified: April 2002
Additional relevant MeSH terms:
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Heart Diseases
Vascular Diseases
Cardiovascular Diseases
Hypertension, Pregnancy-Induced
Pregnancy Complications
Calcium, Dietary
Calcium-Regulating Hormones and Agents
Physiological Effects of Drugs
Bone Density Conservation Agents