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Calcium supplementation during pregnancy for preventing hypertensive disorders and related problems

  1. G Justus Hofmeyr1,*,
  2. Álvaro N Atallah2,
  3. Lelia Duley3

Editorial Group: Cochrane Pregnancy and Childbirth Group

Published Online: 19 JUL 2006

Assessed as up-to-date: 1 MAR 2006

DOI: 10.1002/14651858.CD001059.pub2


How to Cite

Hofmeyr GJ, Atallah ÁN, Duley L. Calcium supplementation during pregnancy for preventing hypertensive disorders and related problems. Cochrane Database of Systematic Reviews 2006, Issue 3. Art. No.: CD001059. DOI: 10.1002/14651858.CD001059.pub2.

Author Information

  1. 1

    University of the Witwatersrand, University of Fort Hare, Eastern Cape Department of Health, Department of Obstetrics and Gynaecology, East London Hospital Complex, East London, Eastern Cape, South Africa

  2. 2

    Universidade Federal de São Paulo / Escola Paulista de Medicina, Brazilian Cochrane Centre, São Paulo, SP, Brazil

  3. 3

    University of Leeds, Centre for Epidemiology and Biostatistics, Bradford, West Yorkshire, UK

*G Justus Hofmeyr, Department of Obstetrics and Gynaecology, East London Hospital Complex, University of the Witwatersrand, University of Fort Hare, Eastern Cape Department of Health, Frere and Cecilia Makiwane Hospitals, Private Bag X 9047, East London, Eastern Cape, 5200, South Africa. gjh@global.co.za.

Publication History

  1. Publication Status: Edited (no change to conclusions)
  2. Published Online: 19 JUL 2006

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Abstract

  1. Top of page
  2. Abstract
  3. Plain language summary

Background

Pre-eclampsia and eclampsia are common causes of serious morbidity and death. Calcium supplementation may reduce the risk of pre-eclampsia through a number of mechanisms, and may help to prevent preterm labour.

Objectives

To assess the effects of calcium supplementation during pregnancy on hypertensive disorders of pregnancy and related maternal and child outcomes.

Search strategy

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (February 2006), the Cochrane Central Register of Controlled Trials (The Cochrane Library, 2005, Issue 4), and contacted study authors. We updated the search of the Cochrane Pregnancy and Childbirth Group's Trials Register on 31st October 2009 and added the results to the awaiting classification section of the review.

Selection criteria

Randomised trials comparing at least one gram daily of calcium during pregnancy with placebo.

Data collection and analysis

We assessed eligibility and trial quality, extracted and double-entered data.

Main results

Twelve studies of good quality were included. The risk of high blood pressure was reduced with calcium supplementation rather than placebo (11 trials, 14,946 women: relative risk (RR) 0.70, 95% confidence interval (CI) 0.57 to 0.86). There was also a reduction in the risk of pre-eclampsia associated with calcium supplementation (12 trials, 15,206 women: RR 0.48, 95% CI 0.33 to 0.69). The effect was greatest for high-risk women (5 trials, 587 women: RR 0.22, 95% CI 0.12 to 0.42), and those with low baseline calcium intake (7 trials, 10,154 women: RR 0.36, 95% CI 0.18 to 0.70).

The composite outcome maternal death or serious morbidity was reduced (4 trials, 9732 women; RR 0.80, 0.65 to 0.97). Almost all the women in these trials were low risk and had a low calcium diet. Maternal deaths were reported in only one trial. One death occurred in the calcium group and six in the placebo group, a difference which was not statistically significant (RR 0.17, 95% CI 0.02 to 1.39).

There was no overall effect on the risk of preterm birth (10 trials, 14,751 women: RR 0.81, 95% CI 0.64 to 1.03), or stillbirth or death before discharge from hospital (10 trials 15,141 babies; RR 0.89, 95% CI 0.73 to 1.09).

Blood pressure in childhood has been assessed in one study: childhood systolic blood pressure greater than 95th percentile was reduced (514 children: RR 0.59, 95% CI 0.39 to 0.91).

Authors' conclusions

Calcium supplementation appears to almost halve the risk of pre-eclampsia, and to reduce the rare occurrence of the composite outcome 'death or serious morbidity'. There were no other clear benefits, or harms.

[Note: The 15 citations in the awaiting classification section of the review may alter the conclusions of the review once assessed.]

 

Plain language summary

  1. Top of page
  2. Abstract
  3. Plain language summary

Calcium supplementation during pregnancy for preventing hypertensive disorders and related problems

Calcium supplements help prevent pre-eclampsia, lowers the risk of the woman dying or having serious problems.

Pre-eclampsia is a major cause of death in pregnant women and newborn babies worldwide. Preterm birth (birth before 37 weeks) is often caused by high blood pressure and is the leading cause of newborn deaths, particularly in low-income countries. The review of trials found that calcium supplementation during pregnancy is a safe and relatively cheap means of reducing the risk of pre-eclampsia in women at increased risk, and women from communities with low dietary calcium. Women were also less likely to die or have serious problems due to pre-eclampsia. No adverse effects have been found but further research is needed into the ideal dosage for supplementation.