bkay

I agree. I've not tried to wash precuts, but it sounds like you would lose a lot of the advantages of precuts by washing. You'll have some raveling, so they will no longer be exactly 10X10. My guess is that they were not cut exactly on the straight of grain, but washing will usually put fabric back straight. So, you'll have to deal with that.
If you are making a baby quilt, you won't need much background fabric. I'd just buy some white yardage for the quilt and cut your own 10X10 squares. That way, you won't have any problems.
That's what I would do faced with that choice.
bkay

MicheleC

I would definitely wash the squares. I was looking into washing pre-cuts and came across this video - https://m.youtube.com/watch?v=02S22-ri2EQ. To summarize, she hand washed her small precuts and uses a salad spinner to get the water out. I haven’t tried it yet but it seems like a gentler way that would help prevent raveling.

just janet

I would do as junegerbracht said and buy yardage and pre wash it.