Association between calcium supplementation and gestational hypertension, and preeclampsia: A Meta-analysis of 26 randomized controlled trials

Pre-eclampsia and eclampsia are common causes of morbidity and mortality, especially in low-income countries. Reducing adverse outcomes associated with hypertensive disorders of pregnancy has been the ultimate priority in recent years. We aim to evaluate the association between calcium supplements and preeclampsia and gestational hypertension risk among pregnant women.A systematic literature search was performed in electronic databases from inception to 15th July 2023, including only randomized controlled trials. Odds ratio (OR) were, and their corresponding 95% confidence interval (95% CI).A total of 26 studies with 19969 patients (9,968 patients with calcium supplements and 10,001 patients with placebo group) were included in the analysis. The Pooled analysis of primary outcome shows that calcium supplements reduce the risk of preeclampsia by 44% (OR, 0.56(95%CI: 0.45-0.70), P<0.001), and reduce the risk of gestational hypertension by 20% (OR, 0.80(95%CI: 0.70-0.91), P<0.001) compared to placebo. There was a trend of lower incidence of preterm delivery (OR, 0.88 (95%CI: 0.71-1.09), P=0.23), labor induction (OR, 0.90 (95%CI: 0.78-1.03), P=0.13), small gestational age (OR, 0.70 (95% CI:0.37, 1.32), P = 0.27), low birth weight (OR, 0.90 (95%CI: 0.78-1.03), P=0.13), perinatal mortality (OR, 0.88 (95%CI: 0.71-1.08), P=0.22), and maternal mortality (OR, 0.48 (95%CI: 0.12-1.84), P=0.28) among calcium supplementation group compared with the placebo group, however not able to reach statistical significant.This study shows that calcium supplements are associated with a significant reduction in the risk of preeclampsia and gestational hypertension and a trend toward better maternal and fetal-related outcomes.