If you do feel that the exercise is too intense for you, don't stop exercising, just switch what you are doing to a low-impact exercise that suits you. You'll find you carry the baby much easier in the third trimester if you do keep exercising, particularly if you are involved in something that helps to increase your core strength (like pilates). I'm a big fan of swimming, if for no other reason than it is possible to exercise without being weighed down!

Kerrie