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Trial fails to show benefit of vitamins C, E to reduce complications of pregnancy-associated hypertension in low-risk women

Tuesday, April 13 2010 | Comments

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What's This? Among low-risk, nulliparous women, supplementation with vitamins C and E during pregnancy does not reduce rates of adverse maternal or perinatal outcomes resulting from pregnancy-associated hypertension, according to findings from a large, randomized, double-blind, placebo-controlled trial.

Researchers randomized 10,154 nulliparous women with a low risk for preeclampsia to receive a supplement containing 1,000 mg/day of vitamin C and 400 IU/d of vitamin E or matching placebo, with treatment initiated between the 9th and 16th weeks of pregnancy.

The primary composite outcome of the trial was the occurrence of severe pregnancy-associated hypertension alone or severe or mild hypertension accompanied by elevated liver enzyme levels, thrombocytopenia, elevated serum creatinine levels, eclamptic seizure, medically indicated preterm birth, fetal growth restriction, or perinatal death.

Secondary outcomes included preeclampsia and other maternal and neonatal outcome measures. Outcome data were available for 9,969 women. The 2 treatment groups were similar with respect to both baseline characteristics and study drug adherence.

The primary outcome occurred in 6.1% of the active-treatment group compared with 5.7% of the placebo group (relative risk [RR], 1.07; 95% CI, 0.91-1.25), a nonsignificant between-group difference.

Similarly, in a post hoc subgroup analysis in which patients were stratified by week of pregnancy at randomization (<13 weeks vs >=13 weeks), the RR for the primary outcome was 1.12 (95% CI, 0.89-1.42) among those who initiated treatment before 13 weeks and 1.02 (95% CI, 0.82-1.26) among those who initiated treatment during or after the 13th week of pregnancy, with no significant difference between these 2 subgroups.

There were also no significant differences between active treatment and placebo in rates of preeclampsia (7.2% vs 6.7%, respectively; RR, 1.07 [95% CI, 0.93-1.24) or in other secondary outcome measures.

These findings "provide no support for the use of vitamin C and E supplementation in pregnancy to reduce the risk of preeclampsia or its complications," the study authors concluded. (Roberts JM, et al. N Engl J Med 2010;362:1282-1291.)

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