Dietary intake of vitamin C and vitamin E and the development of hypertensive disorders of pregnancy.

OBJECTIVES

To explore the relationship, if any, between dietary intake of the antioxidant vitamins C and E, and the development of pre-eclampsia and gestational hypertension.

STUDY DESIGN

A prospective cohort study of pregnant women attending the antenatal clinic of the Women's and Children's Hospital in Adelaide, Australia, was carried out between April and July 2001. Women completed a semi-quantitative 116-item food frequency questionnaire (FFQ). Women's medical records were viewed after birth to collect data on pregnancy outcomes. Relationships were explored through cross-tabulations, chi-square analysis, and adjustments were made for potential confounders using binary logistic regression.

RESULTS

A total of 299 women completed the FFQ. Median intake of vitamin C was 188 mg and for vitamin E was 6.74 mg. There was no relationship between the intake of vitamin C and hypertensive disorders of pregnancy. For vitamin E, being in the lowest quartile of intake, was associated with an increased risk of hypertensive disorders (RR 1.75, 95% CI 1.11-2.75, P = 0.02). This relationship was confirmed after adjusting for the confounding factors of maternal age and parity.

CONCLUSIONS

Little support was found for a relationship between dietary intake of vitamin C and the development of hypertensive disorders of pregnancy. Low vitamin E intake was associated with a significant increase in the risk of hypertensive disorders of pregnancy, even after adjustments were made for confounding factors. Further research is required to investigate whether supplementation above dietary intake of antioxidant vitamins influences the risk of hypertensive disorders of pregnancy.