My OB doesn't seem to place much emphasis atall on weight and in fact never weighs me at my visits and from what I've read a lot don't any more. It certainly appears that if you are overweight (even slightly) to start off with your weight gain will be less than if you are the right side of scales to start off with.

As long as you make sure you're eating healthily and baby is growing in accordance to what its supposed to do I understand it is not something to be concerned about.
That being said I do weigh myself each week just to track for myself whats happening. So far about 6.4kg .......... and baby from my 32 week scan that I had on Monday is supposed to be 1.9KG of that.

Friends of mine who tracked like me did say however that their weight increased quite a bit in their last 6 weeks. (Ah joy & happiness what to look forward to )