All cotton fibers shrink with water, hot or cold. If they are made into thread, it will shrink when subjected to water. If it is woven into fabric it will shrink. The warp and weft of fabric will also shrink. The threads used are not generally balanced in both directions. But, cotton fibers made into quilt batting also shrink. I do not pre-wash because I know that all components will shrink when the quilt is washed. The amount of shrinkage is more controlled (at least I think so) when everything is washed at the same time. It depends on the look you are happy with.