Hopefully someone who knows more about fitness will drop on in... I'm certainly no expert
I would think that you can do the excersises your body is used to doing. So if you have a routine you normally follow, it should still be safe to practice this during pregnancy, as long as you are comfortable and listening to your body - if you find anything painful then it is best not to do it.
But I would think that everyone is different, so it is always worth getting an opinion from someone IRT your individual situation.
Also, my dr advised that you shouldn't let your temperature or heart rate get too high. If you get hot, you can sweat to cool yourself down. Your baby can't sweat so can't cool him/herself down.
HTH a little.