This has been an on-going debate. I personally don't pre-wash new fabrics unless they have a "chemically" odor. I ALWAYS wash fabrics from yard sales, thrift shops etc. I was given a box of fabrics the other day that had been sitting in an outdoor shed for years. I opened it outside, with rubber gloves on and pulled the pieces out and shook them before washing them. Lots of insect casings, dead insect carcasses and even a couple of old wasp nest cells. I think it all depends on your own preferences and allergies. BTW, I ALWAYS wash finished baby quilts before gifting them.