Hello,
My DH and I are currently trying to conceive and I am a dancer/dance teacher. I plan to keep dancing throught my pregnancy when it happens. Also there are about 4 or 5 ladies that I dance with who have continued dancing throughout their pregnancy. One of my friends even performed in our annual concert when she was 5 months. Of course you need to know limitations and not do anything ridiculuous but it is very healthy to keep up the exercise and as you say if you are fit before you fall pregnant and you know your body then good on you!!!