My son is 17 mths old & has hit all his milestones. he can say 5-10 words not clearly but you can tell he is trying to repeat. he smiles, loves to be around everyone. he head bangs off his crib mattress when he's tired though. sign of autism?

Head banging on its own without any other indications of autism, is not diagnostic or even concerning. Up to 15% of non-autistic infants/toddlers head bang their heads to self sooth.

Head banging is common at this age. Behavior modification involves re enforcing and rewarding the behavior change. Soothing music, a bedtime story and then placing him in the crib may be helpful. Please follow up with your physician.

Not necessarily but I would bring it to the attention of his pediatrician so he can evaluate him with diagnostic studies to determine if this is an early sign of autism or not.

As he is meeting his developmental milestones and is socially interactive, it does not sound like his head banging is a sign of autism for him. This is especially true if he is not doing this at other times during the day when he's frustrated or for no reason. As he gets older, he will likely stop doing this to fall asleep. Please also discuss this with his pediatrician.