Very many
Do not worry for such child if the doctor considers that it is healthy.
Very many children, having learned to rise, do not know how again to sit down.
Poor the crumb can stay some hours, will not fall down from exhaustion yet.
When mother puts such child, having torn off him from a handrail of a bed or an arena, he instantly forgets about fatigue and is again brought up and gets up.
But this time he starts crying already in a few minutes.
The only thing that mother can undertake, allow to it to play any interesting subject longer to hold it in a sitting position.