Calcium Metabolism in Preeclampsia: Supplementation May Help

Calcium homeostasis is an important aspect of maternal and fetal physiology during gestation, since fetal bone mineralization requires adaptive adjustments in maternal calcium regulation. In the third trimester, for example, calcium is deposited in the fetal skeleton at the rate of 200mg/day. In addition, women double their urinary excretion of calcium in the third trimester. Recent studies have implicated alterations in calcium metabolism in the pathogenesis of hypertension during pregnancy. Deficiencies in calcium intake have been linked to preeclampsia/eclampsia. Further, hypocalciuria and deviations in levels of 1,25-dihydroxyvitamin D and parathyroid hormone have been shown in women with preeclampsia. In one study, calcium supplementation was associated with an approximately 50% decrease in the risk of all types of pregnancy-induced hypertension. The risk of preeclampsia was between 45% and 74% lower for women who received calcium supplementation. At present, several trials of calcium supplementation in pregnancy are in progress. One, an NIH-sponsored study that will enroll more than 4000 patients, is nearing completion.