Combined vitamin C and E supplementation during pregnancy for preeclampsia prevention: a systematic review

The effect of combined vitamin C and E supplementation during pregnancy on the prevention of preeclampsia and major adverse infant outcomes has been reviewed. We searched MEDLINE and the Central Library of Controlled Trials of the Cochrane Library through August 2006 for relevant clinical trials. Interstudy heterogeneity was evaluated using the chi(2) statistic (Q statistic) test. Pooled relative risks (RRs) and 95% confidence intervals (CIs) were calculated with a fixed or random-effects model as appropriate. Four trials that collectively randomized 4680 pregnant women to either the combination of vitamin C and vitamin E or placebo were included in the analysis. There were no significant differences between the vitamin and placebo groups in the risk of preeclampsia, 11% versus 11.4%, RR 0.97 (95% CI 0.82-1.13), fetal or neonatal loss, 2.6% versus 2.3%, RR 1.10 (95% CI 0.78-1.57), or small for gestational age (SGA) infant, 20.6% versus 20%, RR 0.94 (95% CI 0.74-1.19). Although there was a higher risk for preterm birth in the vitamin group, 19.5% versus 18%, RR 1.07 (95% CI 0.96-1.20), this finding was not significant. Combined vitamin C and E supplementation during pregnancy does not reduce the risk of preeclampsia, fetal or neonatal loss, small for gestational age infant, or preterm birth. Such supplementation should be discouraged unless solid supporting data from randomized trials become available. TARGET AUDIENCE: Obstetricians & Gynecologists, Family Physicians LEARNING OBJECTIVES: After completion of this article, the reader should be able to recall that many methods have been used to prevent preeclampsia, state that increased oxidative stress has been postulated and many trials have used antioxidants to prevent the disease, and explain that MEDLINE analysis of the literature questions the use of vitamin C and E supplements.