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Oral Calcium in Pregnant Women With Hypertension

This study has been completed.
Information provided by:
National Heart, Lung, and Blood Institute (NHLBI) Identifier:
First received: October 27, 1999
Last updated: May 12, 2016
Last verified: April 2002
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 Intervention Phase
Cardiovascular Diseases Heart Diseases Hypertension Pre-Eclampsia Pregnancy Toxemias Vascular Diseases Behavioral: dietary supplements Drug: calcium Phase 2

Study Type: Interventional
Study Design: Allocation: Randomized
Masking: Double
Primary Purpose: Prevention

Resource links provided by NLM:

Further study details as provided by National Heart, Lung, and Blood Institute (NHLBI):

Study Start Date: August 1993
Study Completion Date: July 1999
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.


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

Publications: Identifier: NCT00000543     History of Changes
Other Study ID Numbers: 86
R01HL048846 ( U.S. NIH Grant/Contract )
Study First Received: October 27, 1999
Last Updated: May 12, 2016

Additional relevant MeSH terms:
Hypertension, Pregnancy-Induced
Cardiovascular Diseases
Heart Diseases
Vascular Diseases
Pregnancy Complications
Calcium, Dietary
Bone Density Conservation Agents
Physiological Effects of Drugs processed this record on September 21, 2017