There’s no reason for a woman to avoid peanuts during pregnancy unless she is allergic.

Children may be less likely to develop nut allergies if their mothers eat nuts during pregnancy, a study has shown.

Scientists analysed data on more than 8000 American children, including 140 who had peanut or tree nut allergies.

Those with non-allergic mothers who ate nuts five times a week or more turned out to have the lowest risk of the allergies.

The findings show that mothers-to-be may have been wrongly advised in the past to avoid nuts.

“Our study showed increased peanut consumption by pregnant mothers who weren’t nut allergic was associated with lower risk of peanut allergy in their offspring,” said US lead researcher Dr Michael Young, from Boston Children’s Hospital.

“Assuming she isn’t allergic to peanuts, there’s no reason for a woman to avoid peanuts during pregnancy.”

At the end of the 1990s it was widely assumed that consuming nuts risked sensitising children, making them more susceptible to nut allergies.

For years mothers in the US were advised to avoid all nuts while pregnant and breast feeding and to keep their children away from peanuts until they were three years of age.

But because of lack of evidence, the guidance was rescinded in 2008.

In the US, the prevalence of childhood peanut allergy has more than tripled from 0.4 per cent in 1997 to 1.4 per cent in 2010.

“No one can say for sure if the avoidance recommendation for peanuts was related to the rising number of peanut allergies seen in the late 1990s and early 2000s. But one thing is certain: it did not stop the increase,” Dr Young added.

“It was clear that a new approach was needed, opening the door for new research.”

He stressed that the findings, published in the journal JAMA Pediatrics, only showed an association, not a cause-and-effect relationship.

“We can’t say with certainty that eating more peanuts during pregnancy will prevent peanut allergy in children,” said Dr Young.

“But we can say that peanut consumption during pregnancy doesn’t cause peanut allergy in children.

“By linking maternal peanut consumption to reduced allergy risk we are providing new data to support the hypothesis that early allergen exposure increases tolerance and reduces risk of childhood food allergy.”

British expert Dr Adam Fox, consultant children’s allergist at Guy’s and St Thomas’s NHS Foundation Trust in London, said: “The results of this study are interesting but are contradictory with other studies that have either shown no effect of nut consumption during pregnancy or suggested a possible risk from increased consumption.

“To make things even more complicated, there is also strong evidence to suggest that nut allergy doesn’t develop until after birth and that it is exposure of the infant’s skin to nut protein that is most important in the development of allergy.

“With such differing results from different studies, it is currently impossible to offer advice about exactly what mothers should do regarding nut consumption during pregnancy but current international guidance is that there is no need to either avoid nuts, nor to actively eat them.”