Something characteristic of babies and young children is that they put anything in their mouth.
Sometimes we can even become anguished when we think that the reason why our baby sucks his hands with relish is hunger. Nothing could be further from the truth.
Babies and young children put objects in their mouths because they are in what is known as oral phase of psycho-affective development. During this phase, the main organ for exploring the environment is the mouth. By introducing objects into it, they obtain information about them and about the world around them. Lasts up to about 3 years of age.
The fact of being in the oral phase of development also means that the baby and young child need suck for pleasure, calm and security. We can clearly observe it in a newborn baby. If we leave it on its mother and facilitate access to the breast, it will look for the nipple and begin to suck. Not because they are hungry, since their need for nutrition is covered thanks to the umbilical cord, but because it is a way of feeling safe and connected with mom.
In older babies we can see how they calm down with the sucking of the finger or the pacifier, if they use it.
Breastfed babies practice what is known as non-nutritive suction: they suckle but without obtaining milk.
No matter how many explanations we give them, we cannot prevent them from trying to put any object in their mouth. It is a necessity and also, they do not understand that it is something dangerous for them, no matter how many explanations we give. We can be guided by our common sense and avoid only objects that pose a risk to your health and safety.