The study reverses 1990s recommendations that mothers stay away from highly allergenic foods like peanuts, tree nuts and shellfish during pregnancy and while nursing. Pediatricians also asked parents not to give children peanuts before the age of three.
None of these recommendations were backed by scientific studies, however, though they were embraced by the American Academy of Pediatricians.
Researchers studied data from The Growing UP Today Study (GUTS) from 1990 to 1994, which included records of 8,000 children, 140 of whom had peanut allergies.
They examined the diets of mothers of children with the peanut allergy before and after their pregnancy, specifically whether they ate nuts, and compared it to the diets of women whose children had not developed the allergy.
The team found that the number of peanut allergies was lower in children whose mothers ate peanuts during and after pregnancy. Dr. Michael Young, of Children's Hospital, said that this can only be thought of as an association and not a cause-effect relationship.
"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 didn't stop the increase," Young said.
The American Academy of Pediatricians took back their recommendation when it was found that the number of peanut allergy cases tripled despite this directive.
"At this point, the data are not strong enough to prove that eating more peanuts during pregnancy will prevent a peanut allergy," Young said. "But we can say that eating peanuts during pregnancy doesn’t cause peanut allergy in children.