If you haven't taken her to the vet by now... You need to put her to sleep. The babies are not going to come on her own and you need to end her suffering. It is very wrong to leave an animal overnight who could be bleeding internally or have toxemia because you couldn't get her to a vet just to put her to sleep. Regardless of whether or not these animals are for food purposes or for pets, we have a duty to take care of them while they are with us. We can't just stand aside and "let nature take its course...". That poor rat could take 3 or more days to die.

I hope you do the right thing very soon and end her suffering. Next time you breed rats, make sure they are over 4 months and under 12-14 months. This will help get rid of any problems associated with birthing.