When do i need to take down the mobile hanging over my child's crib?

When baby grabs it: When junior is tall enough to grab it, down it will come. You can remove it entirely, or hang it from a higher loop from the ceiling, well out of reach.

Mobile movement: A good time to take a mobile down is when you transfer your child to a regular sized bed from a crib. That way he won't be reaching for it and possibly fall out of bed and injure himself.