Intake of vitamin C and E in pregnancy and risk of pre-eclampsia: prospective study among 57 346 women.

OBJECTIVE

It has been suggested that vitamin C, alone or in combination with vitamin E, may protect against pre-eclampsia, whereas the safety of high-dose vitamin E supplements has been questioned. We investigated dietary intakes of vitamins C and E to see if they correlated with the incidence of pre-eclampsia.

DESIGN

Prospective cohort study.

SETTING

The Danish National Birth Cohort; a population-based pregnancy cohort; analyses were based on 57 346 pregnancies.

METHODS

Vitamin intake was estimated from a food frequency questionnaire completed in gestational week 25, recording intake from diet and supplements during the previous four weeks. Pre-eclampsia diagnoses were obtained from the Danish National Patient Registry; we worked with two entities, 'pre-eclampsia (all types)' and 'severe pre-eclampsia/eclampsia/HELLP'. We adjusted for confounding factors by logistic regression.

MAIN OUTCOME MEASURES: A small increase in the incidence of severe disease was also seen in the group of women (64, n = 49 373) with a high intake of vitamin E from supplements and dietary sources.

RESULTS

The incidence of 'pre-eclampsia (all types)' did not correlate with dietary vitamin C and E intake. There was a decreasing trend (P = 0.01) in the incidence of 'severe pre-eclampsia/eclampsia/HELLP' with increasing dietary vitamin C intake; with an intake of 130-170 mg/day as reference, odds ratios ranged from 1.21 (95% confidence interval 0.83 to 1.75) for an intake below 70 mg/day to 0.70 (0.40 to 1.23) for an intake exceeding 275 mg/day (total n = 57 346). For vitamin E intake aggregated from diet and supplements (n = 49 373), with an intake of 10.5-13.5 mg/day as reference, the 'severe pre-eclampsia/eclampsia/HELLP' odds ratio was 1.46 (1.02 to 2.09) for an intake exceeding 18 mg/day.

CONCLUSIONS

Low dietary intake of vitamin C was associated with a trend towards an increased incidence of either severe pre-eclampsia, eclampsia or HELLP. A small increase in the incidence of severe disease was also seen in the group of women with a high intake of vitamin E from supplements and dietary sources.