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Calcium Found Not to Prevent Preeclampsia

Several studies suggest that calcium supplementation prevents gestational hypertension and preeclampsia. This large, randomized, blinded trial did not find such a benefit.

Researchers randomized 4,589 healthy nulliparous women between 11 and 21 weeks of pregnancy to 2 g daily of elemental calcium or placebo. Patients were assessed for hypertension and proteinuria every four weeks through the second trimester and weekly during the last five weeks of pregnancy. About 65% of women in each group complied with treatment.

Overall, there was no difference between treatment groups in the incidence of hypertension, proteinuria, or preeclampsia: Preeclampsia occurred in 6.9% of the calcium group and 7.3% of the placebo group (relative risk, 0.94; 95% CI, 0.76 to 1.16). Nor was outcome affected by baseline levels of dietary calcium (based on 24-hour urinary calcium measurement) or maternal age. Obstetric and perinatal outcomes were similar in the two groups.

Comment: Preeclampsia affects about 5% of pregnancies, and calcium supplements appear not to prevent it. This study demonstrates the usefulness of large randomized, controlled trials to assess the benefit of treatments for common conditions.

— W Levinson

Published in Journal Watch Women's Health August 1, 1997

Citation(s):

Levine R et al. Trial of calcium to prevent preeclampsia. N Engl J Med 1997 Jul 10 337 69-76.

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