Most clothes that you buy at a store have been steamed to get out any wrinkles. I don't think that a one-time, light steaming will shrink the fabric much. That being said, I do not steam my quilting pieces, unless I have something that is really stubborn and giving me a hard time. I usually just finger press my pieces as I put them together. The pieces are small and even an 1/16th of an inch shrinkage can make a big difference in the final product.