"We were pretty surprised to see the adverse associations between daily vs. rare nut product consumption during pregnancy and symptoms of asthma in children, because we haven't seen this in similar previous studies," lead author Saskia M. Willers of Utrecht University, the Netherlands, said in a statement.
It is "too early to make recommendations of avoidance," but "it's important for pregnant women to eat healthily, and what is true for many foods is that too much is never good."
In a study by the Dutch government, nearly 4,000 expectant mothers completed a dietary questionnaire that asked how often they consumed vegetables, fresh fruit, fish, eggs, milk, milk products, nuts and nut products during the past month. Their children's diets were also assessed. Asthma and allergy symptoms were assessed yearly in the children until age 8.
"The only consistent association between the maternal intake of the investigated food groups during pregnancy and childhood asthma symptoms until 8 years of age that we found was with nut products," Willers said.
The study is published in the American Journal of Respiratory and Critical Care Medicine.