The new study, published Monday in the journal Pediatrics, found that food allergy rates in children under 3 fell after those guidelines were put into place — dropping to 0.93 percent between 2017 and 2020, from 1.46 percent between 2012 and 2015. That’s a 36 percent reduction in all food allergies, driven largely by a 43 percent drop in peanut allergies.