Ilovemybed I think depending on the type of job you do it could be quite easy to get signed off with carpal tunnel.
I could have this time round but decided just to go for annual leave and then mat leave from 36 weeks.
But last time my left hand was agony, really couldn't grip anything, constantly had shooting pains up my arm through my wrist and into my thumb.
As I was coming to the end of work I had little to do so I was assigned to take someone who couldn't drive to site meetings etc as it was crazy for them to give me a new project to start for 4 weeks. So when I could no longer grip the steering wheel I decided enough was enough.
But it doesn't get better so you'd need to be signed off for the rest of your pregnancy, are you near the end or do you want a month off but to go back?