My baby is 3 month 23 days old when I take him in my lap from the floor he can’t make his head straigh.why ?

A. Maam you have to understand this that the child has a partial stability in this age of the head and the total will come by completing the time of six months the head is still very wobbly in this you have to give this part of your hand behind the neck and head of the child so that it can take it support that way with your help