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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)

Tracking Information
First Submitted Date  ICMJE October 27, 1999
First Posted Date  ICMJE October 28, 1999
Last Update Posted Date May 13, 2016
Study Start Date  ICMJE August 1993
Primary Completion Date Not Provided
Current Primary Outcome Measures  ICMJE Not Provided
Original Primary Outcome Measures  ICMJE Not Provided
Change History Complete list of historical versions of study NCT00000543 on Archive Site
Current Secondary Outcome Measures  ICMJE Not Provided
Original Secondary Outcome Measures  ICMJE Not Provided
Current Other Pre-specified Outcome Measures Not Provided
Original Other Pre-specified Outcome Measures Not Provided
Descriptive Information
Brief Title  ICMJE Oral Calcium in Pregnant Women With Hypertension
Official Title  ICMJE Not Provided
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.
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.

Study Type  ICMJE Interventional
Study Phase  ICMJE Phase 2
Study Design  ICMJE Allocation: Randomized
Masking: Double
Primary Purpose: Prevention
Condition  ICMJE
  • Cardiovascular Diseases
  • Heart Diseases
  • Hypertension
  • Pre-Eclampsia
  • Pregnancy Toxemias
  • Vascular Diseases
Intervention  ICMJE
  • Behavioral: dietary supplements
  • Drug: calcium
Study Arms  ICMJE Not Provided
Publications *

*   Includes publications given by the data provider as well as publications identified by Identifier (NCT Number) in Medline.
Recruitment Information
Recruitment Status  ICMJE Completed
Enrollment  ICMJE Not Provided
Original Enrollment  ICMJE Not Provided
Actual Study Completion Date  ICMJE July 1999
Primary Completion Date Not Provided
Eligibility Criteria  ICMJE Pregnant women with chronic hypertension.
Sex/Gender  ICMJE
Sexes Eligible for Study: Female
Ages  ICMJE 18 Years to 40 Years   (Adult)
Accepts Healthy Volunteers  ICMJE No
Contacts  ICMJE Contact information is only displayed when the study is recruiting subjects
Listed Location Countries  ICMJE Not Provided
Removed Location Countries  
Administrative Information
NCT Number  ICMJE NCT00000543
Other Study ID Numbers  ICMJE 86
R01HL048846 ( U.S. NIH Grant/Contract )
Has Data Monitoring Committee Not Provided
U.S. FDA-regulated Product Not Provided
IPD Sharing Statement  ICMJE Not Provided
Responsible Party Not Provided
Study Sponsor  ICMJE National Heart, Lung, and Blood Institute (NHLBI)
Collaborators  ICMJE Not Provided
Investigators  ICMJE Not Provided
PRS Account National Heart, Lung, and Blood Institute (NHLBI)
Verification Date April 2002

ICMJE     Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP