Calcium supplementation during pregnancy for preventing hypertensive disorders and related problems - PubMed (original) (raw)

Meta-Analysis

G J Hofmeyr et al. Cochrane Database Syst Rev. 2006.

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Abstract

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 Trials Register (February 2006), the Cochrane Central Register of Controlled Trials (The Cochrane Library, 2005, Issue 4), and contacted study authors.

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.

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