I'm a luscious larger lady, and I was worried about the combined effect of my weight (>100kg at beginning of preg, but I'm tall) and my age (>35) on things like GD and blood pressure. So I took the step of seeing a dietician throughout my preg, she helped me with a low-GI diet which meant I put on a minimum of weight and more importantly didn't have any issues with GD.

As for other health professionals - no one ever mentioned my weight - not my GP, nor the OB, the only time I was weighed was at the pre-surgical appt (when they weigh and measure your height so they can calculate how much of the drugs to use) for my C/S. I had a shocking case of pelvic laxity (or SPD) but I know just as many tiny ladies who have had this problem and it seems to have nothing to do with weight at all.