Increasing fibre intake during the first three months of pregnancy can reduce the risk of the life-threatening condition by more than half, research shows.
Pre-eclampsia, which is characterised by high blood pressure, affects one in ten expectant mothers and occurs late in the pregnancy.
If it develops into full eclampsia it can endanger the life of the mother and baby.
In some cases, the baby may have to be delivered prematurely. If the condition worsens further, women can suffer fits.
Dr Chunfang Qiu carried out a study of 1,538 women’s diets before conception and during the first three months of pregnancy.
He found those whose diets were rich in grain, fruit and vegetables – more than 21.2g of fibre a day – were two-thirds less likely to develop the condition than those who ate less than 11.9g.
Dr Qiu, who reports his findings on the American Journal of Hypertension website, said adding 5g of fibre to your diet is the equivalent of eating two slices of wholegrain bread.
Dr Qiu, of the Swedish Medical Centre, in Seattle, said: “These results suggest the important health benefits of increased fibre consumption before and during early pregnancy.”