Can having more than 3 scans have a negative effect on the baby?

Usually eating soil or pica as its commonly known is an indication that your baby could be having a deficiency in minerals especially iron.  Lack of iron may also lead to low immunity and appetite.  Your baby could also need deworming due to exposure to parasites in the soil.
Please see your doctor to run a blood test to determine if your baby has particular deficiencies which can then be addressed.