Dear Sandra, It is important to be on the diet whether or not the baby has PKU. The excess protein in your bloodstream acts as an acid and can severly damage the nervous system of the developing baby. And also not to mention, there is no safe way to test for PKU while the baby is in the womb so stay on the diet. Also to the mother who started this. 4.6 is great levels! When i was that age i was jumping from 10 to 15 to 8 to 16. I was always on the diet but ate things I couldnt because I didnt understand why I was allergic to food. You should really start your daughter on the diet because it will help her develop more normally and help in school. Also it is a lot healthier and safer to be on the diet.