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Calcium supplementation during pregnancy for preventing hypertensive disorders and related problems
A N Atallah1, G J Hofmeyr, L Duley
1Escola Paulista de Medicina, Universidade Federal de Sao Paulo, Rue Pedro de Toledo 598, Sao Paulo, Brazil, 04024 900. cochrane.dmed@epm.br
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 and the Cochrane Controlled Trials Register and we contacted study authors.
Selection Criteria:
Randomised trials comparing at least one gram daily of calcium during pregnancy compared to placebo.
Data Collection And Analysis:
Eligibility and trial quality were assessed. Data extraction was carried out independently by two reviewers.
Main Results:
Nine studies were included, all of good quality. There was a modest reduction in high blood pressure with calcium supplementation (relative risk 0.80, 95% confidence interval 0.73 to 0.88). The effect was greatest for women at high risk of hypertension (relative risk 0.35, 95% confidence interval 0.21 to 0.57) 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. 72, 95% confidence interval 0.60 to 0.86). The effect was greatest for women at high risk of hypertension (relative risk 0.22, 95% confidence interval 0.11 to 0.43) 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.
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.