Calcium reduces risk of pre-eclampsia

Abstract

The excellent Seminar on preeclampsia by Eric Steegers and colleagues (Aug 21, p 631) misses an important point regarding the potential of nutritional interventions to prevent pre-eclampsia. Steegers and colleagues state that an evidence-based review found no relation between calcium supplementation and risk reduction for preeclampsia, but that some reduction might be seen in populations that are calcium defi cient. The review cited was a US Food and Drug Administration (FDA) assessment of the scientifi c evidence to substantiate a health claim for calcium supplementation, which excluded all trials in pregnant women with low calcium intakes. A Cochrane systematic review and meta-analysis on double-blind placebo-controlled trials reached a diff erent conclusion. The Cochrane review found that calcium supplementation compared with placebo signifi cantly reduced the risk of high blood pressure (risk ratio 0·65, 95% CI 0·53–0·81), the overall risk of pre-eclampsia (0·45, 0·31–0·65), and especially the risk of pre-eclampsia in high-risk women (0·22, 0·12–0·42) and women with low baseline calcium intakes (0·36, 0·20–0·65). The risk of preterm birth was signifi cantly reduced with calcium (0·76, 0·60–0·97), and more so in women at high risk of pre-eclampsia (0·45, 0·24–0·83). The composite outcome for maternal death or serious morbidity was signifi cantly reduced by calcium supplementation (0·80, 0·65–0·97). A diet that provides 1000 mg per day calcium, or a dietary supplement of calcium (and vitamin D), is a cheap means of reducing the risk of pre-eclampsia in women at increased risk and in women with low calcium intakes, and has other health benefi ts while doing no harm.