The diet of a pregnant woman "has the potential to affect airway development" of the developing foetus in a manner that "might increase the risk of developing childhood asthma or allergy," Saskia M. Willers, of Utrecht University, the Netherlands, and colleagues explain in a report in the American Journal of Respiratory and Critical Care Medicine.
In a study, 4 146 pregnant women provided information on how often they ate fruit, vegetables, fish, egg, milk, milk products, nuts, and nut products during the last month of pregnancy. The researchers then followed the women's children for 8 years, analysing associations between maternal diet during pregnancy and asthma outcomes.
Complete data were available for 2 832 children. Children of mothers who reported daily consumption of nut products had a 42 percent increased risk of wheezing and a 58 percent increased risk of difficulty breathing relative to children of mothers who reported that they rarely ate nut products.
Children of mothers who ate nut products daily also had a 47 percent increased odds of having asthma symptoms and a 62 percent increased odds of using inhaled steroids.
These associations were independent of the child's diet.
"More research is needed to study the effect of exposure to nut or nut products or other allergenic foods during pregnancy, not only on the development of food allergy, but also on the development of asthma and other allergic diseases," the investigators conclude.
"The findings of this study need to be replicated by other studies before influencing dietary advice given to pregnant women," they caution.