VIENNA — A high-fiber diet reduces the risk for preeclampsia in pregnant women, Michelle A. Williams, Sc.D., reported at the 14th World Congress of the International Society for the Study of Hypertension in Pregnancy.
There is a wide body of literature supporting the link between consumption of dietary fiber and reductions in blood pressure, as well as improvements in other cardiovascular risks, such as cholesterol and triglyceride concentrations, insulin sensitivity, and inflammation. Current dietary guidelines, therefore, recommend a diet containing at least five servings of fruits or vegetables daily and a total daily fiber intake of 20-30 g.
Now, similar findings from both a case-control study involving 511 women and a prospective cohort study of 875 women suggest that “current efforts to encourage populations to consume diets high in grains, fruits, and vegetables may also benefit pregnant women,” said Dr. Williams, professor of epidemiology at the University of Washington and associate director of the Center for Perinatal Studies at Swedish Medical Center, both in Seattle.
In the case-control study, 172 women with preeclampsia and 339 controls, retrospectively, completed questionnaires about their diets during pregnancy and in the 3 months before becoming pregnant.
Median daily consumption of carbohydrates was significantly lower in the preeclampsia group (216 g vs. 253 g), as was fiber consumption (18 g vs. 19 g).
The women whose fiber intake placed them in the upper quartile of daily fiber consumption (more than 24 g) were 51% less likely to develop preeclampsia than were those in the lowest quartile (less than 13 g), after controlling for maternal age, parity, adiposity, income, and total caloric consumption.
Because of the potential limitations of this type of study design—including selection and recall bias—Dr. Williams and her colleagues followed this study with a larger prospective study in which the women were given a structured interview at 12 weeks' gestation in addition to the periconceptional dietary intake questionnaire.
Of the 875 women with singleton pregnancies, 62 had preeclampsia. Of those, 23 were among the lowest quartile for daily fiber consumption (less than 11.9 g), while 14 were in the highest quartile (more than 20.7 g). The women with preeclampsia accounted for approximately 10% of the total 222 women in the lowest fiber consumption quartile, compared with just 6% of the 218 in the highest quartile.
After adjustment for total daily calories, age, race or ethnicity, parity, prepregnancy body mass index, and daily vitamin C intake, the relative risk for preeclampsia was reduced by 70% among those whose fiber consumption was in the highest quartile, compared with those in the lowest.
Even when a stricter definition of preeclampsia was used, resulting in the loss of 20 of the 62 women from the analysis, having the highest fiber consumption still cut the preeclampsia risk in half, Dr. Williams reported at the meeting.