WOMEN who eat nut products such as peanut butter every day while pregnant increase their baby's risk of developing asthma by more than 50 per cent.
Dutch researchers found that, compared with women who rarely ate nut products, children of daily eaters were also 58 per cent more likely to have wheeze by the age of eight, 53 per cent more likely to have asthma symptoms and 42 per cent more likely to have laboured breathing.
However, there did not appear to be any association between these symptoms and women who ate plain nuts during pregnancy, The Australian reports.
The authors, whose team based the results on the eating habits of more than 4000 pregnant women in the six weeks before they gave birth, said it was too early to advise pregnant women to avoid nut products.
They also said it was not yet possible to say whether nut products caused the observed effects, or whether some other unidentified factor common to the nut eaters was responsible.
Writing in the American Journal of Respiratory and Critical Care Medicine, the authors said more research was needed to study the effect of exposure to nuts, nut products and other allergenic foods during pregnancy.
Eating nuts during pregnancy has been suspected of having a role in making babies allergic to peanuts, a condition that in severe forms can be life-threatening.
In 1998, British health officials recommended women with a history of allergy avoid eating peanuts while pregnant. Two years later, US experts signalled tentative agreement.
An accompanying editorial in the journal said neither move appeared to have cut rates of peanut allergy, which remained the main concern over peanut consumption during pregnancy.
The case that eating nut products might be the cause of the asthma symptoms was "not compelling", the editorial said.
Respiratory physician and allergist Janet Rimmer, of the Woolcock Institute of Medical Research in Sydney, said the finding was an interesting observation but more evidence would be required to make specific recommendations to women.