Vitamin C and vitamin E in pregnant women at risk for pre-eclampsia (VIP trial): randomised placebo-controlled trial. Vitamin D supplementation in pregnancy: a controlled trial of two methods.
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.
                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 alpha 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 .
                Of 2404 patients treated, we analysed 2395 (99.6%). The incidence of pre-eclampsia was similar in treatment 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]).
                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. A randomized study was conducted to evaluate the effects of single-dose and daily vitamin D supplementation in pregnant women during the last trimester of a winter pregnancy in the Northwest of France. The women were divided into three randomized groups: one (N = 21) was given a vitamin D2 supplement of 1000 IU/day during the last three months of pregnancy, one (N = 27) was given a single oral dose of 5 mg at the seventh month of pregnancy, and one (N = 29) acted as a control. Venous plasma samples were obtained at delivery from the women and from cord blood, and levels of calcium, 25-OHD, and 1,25(OH)2D were determined. No significant difference in plasma calcium concentration was found among the three groups, but within each group plasma calcium concentrations were higher in the cord samples than in the respective maternal samples. The levels of the two metabolites measured were consistently lower in the cord samples than in the respective maternal samples. Cord 25-OHD concentrations correlated with those of maternal plasma. No significant modification of maternal calciuria or of the birth weight of term infants was observed. 25-OHD concentrations were greater in maternal and cord plasma from treated mothers, but only a slight difference was observed between the supplemented groups. 1,25(OH)2D concentrations were not significantly different in the three groups. A single 5-mg dose of vitamin D given orally at the seventh month of pregnancy provides effective prophylaxis in the authors' region.
The data are too few to say if vitamin E supplementation either alone or in combination with other supplements is beneficial during pregnancy.
[Note: The 24 citations in the awaiting classification section of the review may alter the conclusions of the review once assessed.]