Calcium supplementation has been proposed to lower the risk of pre-eclampsia, a major contributor to maternal and neonatal complications, yet its preventive effectiveness remains unclear. To address this uncertainty, a large study evaluated whether calcium supplementation reduces the incidence of hypertensive disorders of pregnancy, involving 37,504 participants. The study showed that calcium supplementation produced little to no reduction in pre-eclampsia (risk ratio (RR) 0.83; sensitivity analysis RR 0.92) and offered very uncertain effects on maternal death (RR 0.33), adverse effects (RR 2.16), and preterm birth (RR 0.83; sensitivity analysis RR 0.97).
It also resulted in minimal differences in maternal death or severe morbidity (RR 0.80), perinatal loss (RR 0.93), and stillbirth (RR 0.91). Comparing low- versus high-dose calcium showed similarly negligible differences across…
