Mattress pads can add softness to your bedding and adds great absorbency to soak up any leaks that the puddle pads repel. See, the liquid will sit on top of the puddle pad because the puddle pad's job is to repel liquids. The mattress pad goes on top of the puddle pad to soak up the liquids making it easier to deal with and pulling the wetness away from your baby. Then you can toss both in the wash!