What symptoms will show when your baby has a lack of iron in her body?

Few if any: Pallor and lack of energy will eventually show in a kid with low iron. Iron is one of the required/rate limiting factors in blood production and kids can be iron deficient for months/years before it is recognized by a lay person. A simple pinprick test of blood hemoglobin is done routinely in wellness kid exams to pick up the problem before it is suspected.