You should pay attention to thumb-sucking is when the baby first tries to do it, not when he finally succeeds. I make this point because there are lot of babies who, for the first few months of their lives, haven't much control over their arms. You see such a baby struggling to get his hands up, and searching around with his mouth. If ny good luck he gets his fist to his mouth, he sucks it vigorously as long as it happens to stay there. This baby, just as much as the real thumb-sucker, is showing a need to such longer at the breast or bottle.
In most cases thumb-sucking was very mild. Many babies do a little thumb-sucking off and on. They get over it quickly, whether you do anything or not. I think, that restraints only make the confirmed thumb-sucker do it more in the long run.
