Background: Oxidative stress could play a part in pre-eclampsia, and there is some evidence to suggest that vitamin C and vitamin E supplements could reduce the risk of the disorder. Our aim was to investigate the potential benefit of these antioxidants in a cohort of women with a range of clinical risk factors. Methods: We did a randomised, placebo-controlled trial to which we enrolled 2410 women identified as at increased risk of pre-eclampsia from 25 hospitals. We assigned the women 1000 mg vitamin C and 400 IU vitamin E (RRR α tocopherol; n=1199) or matched placebo (n=1205) daily from the second trimester of pregnancy until delivery. Our primary endpoint was pre-eclampsia, and our main secondary endpoints were low birthweight (<2·5 kg) and small size for gestational age (<5th customised birthweight centile). Analyses were by intention to treat. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN 62368611. Findings: Of 2404 patients treated, we analysed 2395 (99·6%). The incidence of pre-eclampsia was similar in treatment and placebo groups (15% [n=181] vs 16% [n=187], RR 0·97 [95% CI 0·80-1·17]). More low birthweight babies were born to women who took antioxidants than to controls (28% [n=387] vs 24% [n=335], 1·15 [1·02-1·30]), but small size for gestational age did not differ between groups (21% [n=294] vs 19% [n=259], 1·12 [0·96-1·31]). Interpretation: Concomitant supplementation with vitamin C and vitamin E does not prevent pre-eclampsia in women at risk, but does increase the rate of babies born with a low birthweight. As such, use of these high-dose antioxidants is not justified in pregnancy.
Bibliographical noteFunding Information:
This trial was funded by the Wellcome Trust (registered charity number 210183) with additional support from Tommy's the baby charity (registered charity number 1060508).
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