My son started teething at three months and had four teeth by four months, so perhaps he is teething. You could offer cold teething rings or cold wash clothes, breast milk slushies in a mesh feeder (or maybe formula if you don't bf) and see if he is receptive.
One thing to watch I suppose is that sometimes putting fingers in their mouths is a sign of hunger so that could be the case. Other than that the only I can think of is to keep hands relatively clean (within reason), as it's a prime way to pass along pathogens and heaven knows people love to hold and touch babies hands. Touch is important to development, as well as pathogen exposure, but there is also a balance to exposure and the load an immature immune system can handle. As far as the corrolation with putting objects in the mouth, I do not know 
Edited by Asiago - 9/6/11 at 11:33am
