Sometimes children resort to thumb sucking as a soothing measure.
Most babies and children resort to sucking their thumbs or fingers at some point and it is a normal behavior for self-soothing and relieving stress.
Children commonly outgrown this habit by around four years old but may continue until age six.
If your child continues to suck their thumb or fingers past six years old, they could be at risk for developing speech problems, preventing their permanent teeth from erupting correctly and causing shifting of existing teeth resulting in an improperly aligned bite or malocclusion.