Exercise in your first trimester

I have been taking workout classes over my lunch hour at my work for the past 2 years -- but now I'm wondering if some of my exercises are safe now that I'm pregnant. I'm 6 weeks and am worried that some of the V-ups (laying on your back and touching your hands to your feet using your abs to pull you upward) and supermans (laying flat on your stomach and lifting you hands and feet up) we do in class are safe. Has anyone else continued these exercises since being pregnant? I don't have my doctors appointment for another 3 weeks and have read online that most exercises are safe - but I am still worried.