Does Calcium Supplementation Reduce Risk for Recurrent Preeclampsia?

Hypertensive disorders of pregnancy, including preeclampsia and eclampsia, are a leading cause of maternal and neonatal morbidity and mortality. To study the effects of calcium supplementation from before pregnancy through 20 weeks' gestation on risk for recurrent preeclampsia, WHO investigators randomized 1355 women from countries with low dietary calcium intake and personal histories of preeclampsia or eclampsia to calcium supplementation (500 mg daily) or placebo. From 20 weeks' gestation on, both groups received calcium supplementation (1500 mg daily).

Prevalence of preeclampsia was similar in both groups (calcium, 23%; placebo, 29%; risk ratio, 0.80).