I was 86kg when Jacob was conceived and I didn't have a problem with my blood pressure or gestational diabetes at all.

I retained STACKS of fluid though (I gained 17.5kg!!) and got carpal tunnel syndrome as a result! I remember mentioning my weight gain to my OB (who didn't weigh me at all during my PG) who said to me that weight gain (or even weight loss) during PG is of little importance (unless it is associated with other things like high blood pressure etc etc) - the main thing is that the baby is growing as it should. He also told me how I'd be surprised how much of the weight I had gained was actually fluid - and he was absolutely right. Only a few weeks after Jacob was born, I had lost all of that weight, bar 2kg.......no wonder I had puffed up like a balloon!!!