Obstetrics & Gynecology

Skip Navigation LinksHome > December 2007 - Volume 110 - Issue 6 > Antioxidant Therapy to Prevent Preeclampsia: A Randomized Co...
Obstetrics & Gynecology:
doi: 10.1097/01.AOG.0000289576.43441.1f
Original Research

Antioxidant Therapy to Prevent Preeclampsia: A Randomized Controlled Trial

Spinnato, Joseph A. II MD1; Freire, Salvio MD2; Pinto e Silva, Joao Luiz MD3; Cunha Rudge, Marilza Vieira MD4; Martins-Costa, Sérgio MD5; Koch, Matthew A. MD6; Goco, Norman6; Santos, Cleide de Barros MD2; Cecatti, Jose Guilherme MD3; Costa, Roberto MD4; Ramos, José Geraldo MD5; Moss, Nancy PhD7; Sibai, Baha M. MD1

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Abstract

OBJECTIVE: To study whether antioxidant supplementation will reduce the incidence of preeclampsia among patients at increased risk.

METHODS: A randomized, placebo-controlled, double-blind clinical trial was conducted at four Brazilian sites. Women between 12 0/7 weeks and 19 6/7 weeks of gestation and diagnosed to have chronic hypertension or a prior history of preeclampsia were randomly assigned to daily treatment with both vitamin C (1,000 mg) and vitamin E (400 International Units) or placebo. Analyses were adjusted for clinical site and risk group (prior preeclampsia, chronic hypertension, or both). A sample size of 734 would provide 80% power to detect a 40% reduction in the risk of preeclampsia, assuming a placebo group rate of 21% and α=.05. The α level for the final analysis, adjusted for interim looks, was 0.0458.

RESULTS: Outcome data for 707 of 739 randomly assigned patients revealed no significant reduction in the rate of preeclampsia (study drug, 13.8% [49 of 355] compared with placebo, 15.6% [55 of 352], adjusted risk ratio 0.87 [95.42% confidence interval 0.61–1.25]). There were no differences in mean gestational age at delivery or rates of perinatal mortality, abruptio placentae, preterm delivery, and small for gestational age or low birth weight infants. Among patients without chronic hypertension, there was a slightly higher rate of severe preeclampsia in the study group (study drug, 6.5% [11 of 170] compared with placebo, 2.4% [4 of 168], exact P=.11, odds ratio 2.78, 95% confidence interval 0.79–12.62).

CONCLUSION: This trial failed to demonstrate a benefit of antioxidant supplementation in reducing the rate of preeclampsia among patients with chronic hypertension and/or prior preeclampsia.

CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, www.ClinicalTrials.gov, NCT00097110

LEVEL OF EVIDENCE: I

© 2007 The American College of Obstetricians and Gynecologists

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