The amount of extra sucking babies do when they are not feeding varies. This extra sucking is a beneficial self-comforting behavior.
Some babies suck on their thumb or fingers almost constantly.
If you have a baby like this, you may want to try to interest him in a pacifier. To be an accepted substitute for the thumb, the pacifier has to be introduced during the baby's first two months. The orthodontic type of pacifier is best because it prevents tongue-thrusting during sucking, but the regular type usually causes no problems. Use trial and error to find the shape your baby prefers. The biggest advantage of a pacifier is that if you can get your child to use one, he won't suck his thumb.