Serum Calcium and Magnesium Levels in Women Presenting with Pre-eclampsia: A Systematic Review and Meta-analysis Based on Observational Studies

Background: Multiple studies have investigated the serum concentrations of calcium (Ca) and magnesium (Mg) in preeclampsia, but the results have been contradictory. The objective of this systematic review and meta-analysis was to examine the association between serum calcium and magnesium levels in patients with preeclampsia and those in the healthy pregnancies.Materials and Methods: A comprehensive search was conducted in various online databases, including PubMed/Medline, Scopus, Embase, Web of Sciences, and Cochrane library to identify relevant studies on Ca and Mg levels in preeclampsia up to July 2023. Inter-study heterogeneity across the included studies was assessed using the chi-square test and I2 statistic. Pooled effect size (ES) was calculated as weighted mean differences (WMDs) with corresponding 95% confidence intervals (CI).Results: A total of 76 articles (comprising 92 studies) were included, with a combined sample size of 10,482 participants (preeclampsia: n=3,991; controls: n=6,491). The random-effects mod-el revealed significantly lower levels of calcium (WMD=-0.807 mg/dL, 95% CI:-0.983,-0.632, P<0.01) and magnesium (WMD=-0.215, 95% CI:-0.338,-0.092, P<0.01) in women with pre-eclampsia compared to the control group. However, the overall pooled WMD for calcium and magnesium levels did not significantly change when individual studies were excluded one by one.Conclusion: This meta-analysis demonstrates that the circulating levels of calcium and magnesium in patients with preeclampsia are significantly lower than those in the control group.