I have three children and I feel that one can one's baby is happy when you look into the baby's eyes and there is spark, and that spark you will see in happy babies. I mean, other babies too can have that spark, but happy baby will establish that happy spark with the movements of his legs and hands. Lol! I do not know whether you got my theory or not but all I meant was that you can see the happiness in the baby's eyes. My third baby was a really happy baby. I mean all the time. Other two had their moments and hours of happiness. ;p
Hi, When he is looks at you and is happy or his general being looks comfortable that I think means that your baby is a happy baby. When the baby doesn't show discomfort about his surroundings and punches his legs and hand in the air with a smile on his face, means that the baby is happy.
My daughter always says the word happy when she's feeling good. The smile on her face confirms her feeling too!