The higher levels make it easier to take your infant out of the crib, but they’re dangerous when your child is able to pull herself to a standing position. The mattress support’s level should be lowered as needed as baby grows. It should always be set to a level where baby cannot climb out. By the time you child is able to pull to a standing position, the support should be at its lowest setting. Once your child begins to climb or reaches 35” in height, we recommend that you cease using the crib or convert it to a toddler bed.