Thumb Sucking A harmless childhood habit of sucking the thumb for comfort. About half of all children suck their thumbs during infancy, with most starting in the first months of life. Ultrasound pictures of intrauterine life have even shown fetuses...

Infants may use pacifier or thumb or fingers to soothe themselves Thumb sucking is the act of putting the thumb into the mouth and rhythmically repeating sucking contact for a prolonged duration. It can also be accomplished with any piece of skin...