Joanna, for any mothers just about to give birth and up to two weeks old, I do just a little bit of Equine Fresh and then cover it all up with wood shavings. When I didn't do that, I lost two litters from the dust of the equine fresh. Deb had warned me she had the same problem, but I have to see it for myself to believe it.
After seeing that the babies were breathing in the dust and clogging up their noses, I switched to this method and haven't lost any babies since.