I prewash all my fabrics, but not the batting. Most often I have use Warm & White - and only once the Warm & Natural.
I wash in warm, rinse in cold - delicate cycle in a front load so less water and no agitation. I dry on low - less dry setting. They shrink alot! I'm sure it is within the batting specs, and they have that wonderful, soft look, but they are smaller than I would like in some cases.
Is this something you just accept, or do you try to make the quilt 10% larger before washing?
I have a top ready to be put together- the pattern's finished size is right on the edge of acceptable, but not if it shrinks a huge amount.
How do you handle this?

I like the differential shrinkage that happens when I first wash a quilt - and I always wash a quilt before giving it away.

BUT - the king-sized bed quilt I made from DH's pattern shrunk up a little too much for my taste. We've been using it for about 10 years, so clearly it didn't make me reject it entirely, LOL. But I do have plans to make us another in the same pattern with larger borders.

I don't like skimpy.

So - I can't say I answered your question, LOL. If you are in doubt, perhaps you might add another border.

Wow, this is a good question. I have to admit I don't think about it too much on baby or lap quilts. My bed quilts are usually made as huge as I can make them because I love the long overhang, so maybe that's why it hasn't been a problem. Now I have to go look at my old quilts and measure them to see if they seem small to me...

kate