hi kellied, congratulations.
the normal advice is that you can do whatever it is that you were doing, but not starting anything new. there is no harm in doing all those classes, but just watch you dont get too hot and drink a bit more than usual.
i was jogging 3-4 times a week before getting pregnant and have continued that, although i slow to a walk as soon as i feel any twinges and i dont go out when its too hot now. just being sensible. but keep in mind some athletes continue to train at a professional level for much of their preg so doing a few aerobics classes is fine. not only that the fitter you are during preg, the better your body recovers after preg, and there is some evidence that labour goes a bit more smoothly.
good luck