Sure. You could probably just write them a letter yourself, or go see the clerk who sent the summons, and explain you're pregnant and get off the list.
I don't think they will waste any time on u as once u go into Labour they will have to arrange something else anyway.
When I was staying home and taking care of my son, I got summonsed for jury duty and they just had a call-in system where you pushed a button if you had any of their listed reasons (mine was sole parent in charge of infant) and it was all done automatically. I kind of wondered if they would send someone to my house to check up or something, but they didn't.
I actually went to jury duty summons, but I was only 32 weeks at the time. It wasn't too bad. Kinda fun actually. They didn't pick me to be on the jury, of course. I just spent about 4 hours there in the morning. But now I'm off the hook for like 2 years, whereas if I'd gotten out of it, they would have wanted me to come back in 6 months.