You'll definitely be able to tell when your female is going to give birth (picture a large pear with legs and a tail). When she stands up her baby belly will def show. As far as seperating pregnant females etc, that is up to you. I don't separate mine and even leave my males in with the females. Most males will not hurt their own young (none of mine have). I have had first time mothers eat their young though. These same mothers now produce nice sized litters and are really good moms to the pups. Don't be alarmed if they eat their babies the first time around. That being said, not all first time mothers will eat their young either, it is just a possibility. I have also been able to pick up pinks and fuzzies from a litter without any ill effects. I only breed to feed my BP collection and am not a large scale breeder, but when it's time to clean out the tubs I have to move the pinks etc regardless of what momma rat thinks. Anyhow, good luck and I hope they produce for you.