When infants are born, they should sleep on a firm mattress that is free of soft objects. If the mattress is too soft, it can increase the risk of suffocation. When infants are around 1 year old, they can be transitioned to a mattress with a slightly softer surface. The mattress should still be firm enough to support the infant’s body, but it should not be so soft that the infant’s head can sink into the mattress.