Squashed baby?

We have a female who gave birth 4 or 5 days ago, and when we went to clean cages last night we discovered one of her babies had gotten under a piece of "box" she had in there to make a house out of, but had chewed all up. Apparantly she had laid on top of it or something strange because the baby was squashed flat dead under the piece. Does anybody else who provides "houses" have issues with that or do I just need something besides cardboard that she can chew up?

I don't provide housing. They all get a lot of aspen to make a nest and a block of wood. A few quirky females will pile up all of the bedding and the block, and loose food, the kitchen sink over their pups. But, I have never had a squashed pup from a hide.

What kind of wood is your block of wood and where do you get it? Hadn't thought about that.

They are actually just scraps from projects. Completly untreated wood, a lot are 2 x 4's, some 2 x 2's. Chris will just cut them into a bunch of 4 inch long pieces for me. The rats do use them. Some use them more than others, but when they look peed on and yellow, I toss em. Sometimes they last a few weeks that way. I find me females always use them a lot when they have a litter, so I always provide a nice fresh one each week.

Oh yea, we get our wood from home depot. It's closest to us.