Calcium Supplementation for the Prevention of Preeclampsia: Challenging the Evidence From Meta-analyses

( BJOG . 2024;131:1524-1529. doi: 10.1111/1471-0528.17769) For many years, the question of whether calcium supplementation can reduce the risk of preeclampsia in pregnant individuals has been studied. In 2010, a Cochrane review and meta-analyses were published, which included 13 randomized trials with a total of 15730 women. The findings of the publications included a mean risk ratio of 0.45 (95% CI: 0.31-0.65) with the population of women who had the lowest calcium intake being the ones benefiting most. The World Health Organization (WHO) updated its guidelines on calcium supplementation based on this study. Later, additional Cochrane publications cautioned the use of calcium supplementation simply due to possible bias and heterogeneity within the studies included in the 2010 analyses. Further statements were made on the topic, with clarification given that the effect was clear within the population of pregnant mothers with nutritional deficits in calcium, even though there was a high degree of heterogeneity in those studies as well. Additional government agencies in the UK have used these findings in their creation of guidelines for clinical care. This study has a specific goal of investigating the claims made from the Cochrane reviews with extra attention given to how much the smaller trials influenced the meta-analyses.