Was this the female's first litter? Sometimes they just don't "get it" on their first litter. Also, I've heard of mice eating their babies from lack of protein... is the mazuri you are feeding formulated for mice specifically, all rodents, or breeding rodents? I have heard of supplementing their diet with a little cat food while they are pregnant and nursing. Also, as mentioned above, mice get easily stressed, so it is a good idea to only handle them when you need to, and to keep them in a nice quiet area.