Dietary factors that affect the risk of pre-eclampsia

Abstract

Pre-eclampsia affects 3%-5% of pregnant women worldwide and is associated with a range of adverse maternal and fetal outcomes, including maternal and/or fetal death. It particularly affects those with chronic hypertension, pregestational diabetes mellitus or a family history of pre-eclampsia. Other than early delivery of the fetus, there is no cure for pre-eclampsia. Since diet or dietary supplements may affect the risk, we have carried out an up-to-date, narrative literature review to assess the relationship between nutrition and pre-eclampsia. Several nutrients and dietary factors previously believed to be implicated in the risk of pre-eclampsia have now been shown to have no effect on risk; these include vitamins C and E, magnesium, salt, ω-3 long-chain polyunsaturated fatty acids (fish oils) and zinc. Body mass index is proportionally correlated with pre-eclampsia risk, therefore women should aim for a healthy pre-pregnancy body weight and avoid excessive gestational and interpregnancy weight gain. The association between the risk and progression of the pathophysiology of pre-eclampsia may explain the apparent benefit of dietary modifications resulting from increased consumption of fruits and vegetables (≥400 g/day), plant-based foods and vegetable oils and a limited intake of foods high in fat, sugar and salt. Consuming a high-fibre diet (25-30 g/day) may attenuate dyslipidaemia and reduce blood pressure and inflammation. Other key nutrients that may mitigate the risk include increased calcium intake, a daily multivitamin/mineral supplement and an adequate vitamin D status. For those with a low selenium intake (such as those living in Europe), fish/seafood intake could be increased to improve selenium intake or selenium could be supplemented in the recommended multivitamin/mineral supplement. Milk-based probiotics have also been found to be beneficial in pregnant women at risk. Our recommendations are summarised in a table of guidance for women at particular risk of developing pre-eclampsia.

Keywords: blood pressure lowering; dietary patterns; nutrient deficiencies; nutritional treatment; weight management.

Figure 1

The OR for pre-eclampsia and the percentage of women with pre-eclampsia against maternal pre-pregnancy body mass index (BMI). Values are ORs (95% CIs) on a log scale from multilevel binary logistic regression models that reflect the risk of pregnancy complications per pre-pregnancy BMI group compared with the reference group (largest group, 20.0–22.4 kg/m²). The bars represent the percentage of pre-eclampsia per BMI group. Models are adjusted for maternal age, educational level, parity and smoking habits during pregnancy (adapted from Santos et al 8).

Figure 2

Relationship between total dietary fibre intake (g/day) and the risk of pre-eclampsia (solid line), with 95% CI (dotted lines). Arrows indicate previous Recommended Dietary Allowance of 20–30 g/day of total fibre for pregnant women in the USA. The vertical bars along the dietary fibre axis indicate the density of the data (adapted from Frederick et al 37).

Figure 3

(A) Correlation between incidence of pre-eclampsia in various countries and serum/plasma selenium concentration (adapted from Vanderlelie and Perkins [119]). (B) Distribution of toenail selenium concentrations in pre-eclamptic and control subjects. Horizontal bars, median values (adapted from Rayman et al 127).