I stopped at 33 1/2 - but I'm an RN, and to work longer than 34 weeks I would have needed to have a letter from my doctor.

But I was sooooo ready to go on leave! It was not much fun trudging up the hill to the hospital, especially in the middle of the day, in Jan/Feb, and with massively swollen legs (I'm dividing the blame for that between being pregnant, and it being summer - I get a bit swollen every year), and then being on my feet all day. If I did a desk job, I might have been able to work longer...)

I reckon you should ask HRM when you HAVE to stop, and if you can work longer than that if you have a doctors letter, and put in to stop work then. You can always bring the date forward if you need to - a girl I worked with got bad varicose veins with her 3rd pregnancy, and stopped working 2 months before she planned to, because she could hardly walk (she had a large one in her vagina - ouch!).