Normal TSH levels can vary depending on a child's age. Generally, TSH levels are higher in newborns and gradually decrease as the child grows. For instance, the normal range for newborns is typically between 0.5 to 6.0 mIU/L, while for older children, it may range from 0.5 to 4.5 mIU/L. It is important to interpret TSH levels in the context of age-specific reference ranges.