Has anyone had their baby fall back from sitting position?
That is so normal and he will continue to do that off and on for a while until he learns that going backwards when sitting = ouch! Having worked in daycares for many years I have seen children as old as 3 years old repeat this and clunk their heads. Heads are very strong and since it is the back of the head they are hitting the chances of damaging anything is almost nil. They might wind up with a goose egg or a head ache though. Put a boppy pillow around him or other pillows behind him when on really hard surfaces, if it’s carpet it will startle more than hurt him. In fact it is a lesson that baby needs to learn and it will encourage him to keep his balance when sitting because he will begin to remember that if he goes backwards it will hurt. Just like my 5 month old has learned that if he just lets himself flop when he is trying to crawl he will bang his nose, now he just lets his arms slide down slowly when he is tired of lifting his belly off the ground.