Calcium supplementation prevents hypertensive disorders of pregnancy

Preeclampsia, a hypertensive disorder of pregnancy, is a major cause of fetal and maternal morbidity and mortality. Epidemiologic studies have shown an inverse relationship between dietary calcium intake and gestational hypertension. A recent large-scale, randomized, double-blind, placebo-controlled clinical trial has shown that supplementation of pregnant women with 2 g calcium per day from the twentieth week of gestation to term can significantly lower the incidence of hypertensive disorders of pregnancy. The beneficial effect of calcium supplementation was apparent as early as the twenty-eighth week of gestation. The mechanism responsible for the effects of calcium on gestational hypertension is unknown.