How old are the babies? How many adults, counting the mother herself are there in the cage with the babies? How old is the mother and is this her first litter?

Rats are normally excellent mothers but some issues may be causing this. Overcrowding, sudden stress from environment change like very loud, continuing noise, babies that are defective, etc.

I've put a link in here for a page specific to breeding and it does mention some of these issues but something must be up as usually females are good with their babies as are male rats with their young.

Hope you get this sorted out.

~~Jo~~