According to the American Academy of Pediatrics, you can start to wean babies off of u003ca href=u0022https://www.healthychildren.org/English/ages-stages/baby/formula-feeding/Pages/Why-Formula-Instead-of-Cows-Milk.aspxu0022 target=u0022_blanku0022 rel=u0022noreferrer noopeneru0022u003eformula at 12 months u003c/au003ewhen their digestive systems are mature enough to digest cow's milk.