Effectiveness of calcium supplementation in the prevention of gestational hypertension: A systematic review and meta-analysis of randomised controlled trials

Abstract

BackgroundGestational hypertension and related disorders, such as preeclampsia, pose significant risks to maternal and foetal health. Calcium supplementation has been proposed as a preventive measure, but its effectiveness remains debated. This review assess the impact of calcium supplementation in prevention of gestational hypertension. MethodsA comprehensive literature search was conducted across multiple databases, including Scopus, EMBASE, PubMed, Web of Science, CINAHL, Cochrane CENTRAL, from inception to July 2024. Eligibility criteria included studies involving pregnant women at risk of gestational hypertension, comparing calcium supplementation to control group, and reporting on outcomes such as preeclampsia, pregnancy-induced hypertension, HELLP syndrome, preterm birth, and maternal mortality. Data were analysed using a random-effects inverse-variance model to calculate pooled risk ratios (RRs) and assess heterogeneity using Cochran’s Q and I2 statistics. Publication bias was evaluated using funnel plots and Egger’s test. Results22 studies with 39,270 individuals were included. Most studies had higher risk of bias. Calcium supplementation significantly reduced the risk of preeclampsia (pooled RR = 0.606, 95 %CI: 0.483–0.761, p < 0.001) and pregnancy-induced hypertension (pooled RR = 0.870, 95 %CI: 0.759–0.996, p = 0.044). However, it showed no significant effect on HELLP syndrome, preterm birth, or mortality. Heterogeneity was moderate to substantial across outcomes, and publication bias was detected for preterm birth and pregnancy-induced hypertension. ConclusionCalcium supplementation during pregnancy significantly reduces the risk of preeclampsia and pregnancy-induced hypertension, highlighting its value as a cost-effective intervention for improving maternal health. These findings support integrating calcium supplementation into prenatal care strategies, particularly for populations with low dietary calcium intake.