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Meta-Analysis
. 2024 Oct;131(11):1524-1529.
doi: 10.1111/1471-0528.17769. Epub 2024 Feb 1.

Calcium supplementation for the prevention of pre-eclampsia: Challenging the evidence from meta-analyses

David Wright  1 , Alan Wright  1 , Laura A Magee  2 , Peter Von Dadelszen  2 , Kypros H Nicolaides  3
Affiliations
Meta-Analysis

Calcium supplementation for the prevention of pre-eclampsia: Challenging the evidence from meta-analyses

David Wright et al. BJOG. 2024 Oct.

Abstract

Objective: To investigate the validity of the conclusion from Cochrane reviews and meta-analyses that treatment with calcium supplementation during pregnancy reduces the risk for pre-eclampsia by 55%, which has been influential in international guidelines and future research.

Design: Sensitivity analysis of data from Cochrane reviews of trials evaluating high-dose calcium supplementation (of at least 1 g/day) for reduction of pre-eclampsia risk.

Setting: Systematic review and meta-analysis.

Population: The Cochrane reviews and meta-analyses included 13 trials enrolling a total of 15 730 women. Random-effects meta-analysis of these studies resulted in a mean risk ratio (RR, calcium/placebo) of 0.45 (95% confidence interval [CI] 0.31-0.65; p < 0.0001).

Methods: We carried out a sensitivity analysis of evidence from the relevant Cochrane review, to examine the impact of study size.

Main outcome measures: pre-eclampsia.

Results: In the three largest studies, accounting for 13 815 (88%) of total recruitment, mean RR was 0.92 (95% CI 0.80-1.06) and there was no evidence of heterogeneity between studies (I2 = 0). With inclusion of the smaller studies, mean RR decreased to 0.45 and I2 increased to 70%.

Conclusions: In assessment of the effect of calcium supplementation on pre-eclampsia risk, the naive focus on the mean of the random-effects meta-analysis in the presence of substantial heterogeneity is highly misleading.

Keywords: Cochrane reviews; calcium supplementation; meta‐analysis; pre‐eclampsia.

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References

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