Like already said, a lot of first time mom's simply don't know what they're doing. Some times the line itself never have good moms or I've seen certain breeds be more horrible mothers then others or have more issues. They have to be getting adequate food/water/shelter and not being over stressed too. If there was a recent sudden change, that could be it. I've had a few first time goes horribly nervious with unknown people (or animals) even near the space and end up loosing babies that way.
If you plan on doing any more breeding at all though, one thing need to come to terms with is not every kit will make it for one reason or another. Its not every single kid or every other litter, BUT it does happen more then with other animals I know. Even under idea conditions, kits can die unexpectedly.