Hi there,
I have carpul tunnel normally but it definately gets worse with pregnancy.
I think it can be caused by the increased pressure on your upper back due to weight out the front with your belly and growing boobs too. This causes a muscle tension which sends a message into your arm and irritates the tendons which then in turn put pressure on the nerves in your hand causing the carpul tunnel. YKWIM??? I had a bit of massage and that seemed to help relieve the extra pressure on those bits. The same thing happens sometimes in the lower back and legs like sciatic nerve pain for the same reasons.
It is no fun is it? I found I am sleeping more heavily (when I am actually able to sleep) and that contributed too. not sure what to suggest there.