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Calcium supplementation during pregnancy for preventing hypertensive disorders and related problems
A N Atallah1, G J Hofmeyr, L Duley
1Effective Care Research Unit, University of the Witwatersrand, Frere/Cecilia Makiwane Hospitals, Private Bag 9047, East London 5200, Eastern Cape, South Africa. gjh@global.co.za
Insights
Calcium supplementation during pregnancy can reduce the risk of high blood pressure and pre-eclampsia, especially for high-risk women. It also led to fewer low birthweight babies, but did not affect preterm delivery rates.
Area of Science:
- Obstetrics and Gynecology
- Nutritional Science
- Public Health
Background:
- Calcium supplementation is investigated for its potential to prevent pregnancy-related hypertension and preterm labor.
- Understanding calcium's role in maternal health is crucial for improving pregnancy outcomes.
Purpose of the Study:
- To evaluate the impact of calcium supplementation during pregnancy on hypertensive disorders.
- To assess related adverse outcomes for both mothers and children.
Main Methods:
- Systematic review of randomized controlled trials comparing calcium (≥1g/day) with placebo during pregnancy.
- Searched Cochrane Pregnancy and Childbirth Group and Cochrane Controlled Trials Registers.
- Assessed trial quality and extracted data.
Main Results:
- Calcium supplementation modestly reduced high blood pressure (RR 0.81) and pre-eclampsia risk (RR 0.68).
- Benefits were most pronounced in women at high risk for hypertension and those with low dietary calcium intake.
- Reduced incidence of low birthweight babies (RR 0.83) and improved childhood blood pressure were observed; no effect on preterm delivery or stillbirth.
Conclusions:
- Calcium supplementation is beneficial for pregnant women at high risk of gestational hypertension and those with low dietary calcium intake.
- Further research is needed to determine optimal calcium dosage during pregnancy.
Background:
Calcium supplementation may prevent high blood pressure through a number of mechanisms and may help to prevent preterm labour.
Objectives:
The objective of this review was to assess the effects of calcium supplementation during pregnancy on hypertensive disorders of pregnancy and related maternal and child adverse outcomes.
Search Strategy:
We searched the Cochrane Pregnancy and Childbirth Group trials register (October 2001) and the Cochrane Controlled Trials Register (Issue 3, 2001) and we contacted study authors.
Selection Criteria:
Randomised trials comparing at least one gram daily of calcium during pregnancy with placebo.
Data Collection And Analysis:
Eligibility and trial quality were assessed. Data extraction was carried out and double entered.
Main Results:
Eleven studies were included, all of good quality. There was a modest reduction in high blood pressure with calcium supplementation (relative risk 0.81, 95% confidence interval 0.74 to 0.89). The effect was greatest for women at high risk of hypertension (relative risk 0.45, 95% confidence interval 0.31 to 0.66) and those with low baseline dietary calcium (relative risk 0.49, 95% confidence interval 0.38 to 0.62). There was also a modest reduction in the risk of pre-eclampsia with calcium supplementation (relative risk 0.68, 95% confidence interval 0.57 to 0.81). The effect was greatest for women at high risk of hypertension (relative risk 0.21, 95% confidence interval 0.11 to 0.39) and those with low baseline calcium intake (relative risk 0.32, 95% confidence interval 0.21 to 0.49). There was no overall effect on the risk of preterm delivery, although there was a reduction in risk amongst women at high risk of hypertension (relative risk 0.42, 95% confidence interval 0.23 to 0.78). There was no evidence of any effect of calcium supplementation on stillbirth or death before discharge from hospital. There were fewer babies with birthweight < 2500g (RR 0.83, 95% CI 0.71-0.98). In one study, childhood systolic blood pressure > 95th percentile was reduced (RR 0.59, 95% CI 0.39-0.91).
Reviewer'S Conclusions:
Calcium supplementation appears to be beneficial for women at high risk of gestational hypertension and in communities with low dietary calcium intake. Optimum dosage requires further investigation.