I wouldn't isolate her - it's very stressful for the fish to be moved just before giving birth, and she could give birth prematurely, losing all the fry. If you've got hornwort in the tank, the fry should be able to hide from the other fish (from your signature, it seems like you've got a pretty gentle crew in the tank, I wouldn't worry too much). If you've got more than one sword that's pregnant, I'm willing to bet even without isolating them you'll soon be overrun with babies. I kept an angel with my livebearers for population control, and when I lost him a while back, the number of platys in the tank began to grow. I bought a new angel today out of necessity; without a predator, my tank would be absolutely packed within a few months!
