Had a 34 week scan for placental position with DS1, when it was flagged up that he might be a big baby. Measured 6lb 13oz, head circ 35cm (average at birth), femur length 40 weeks +
I was terrified. They asked me to come in for a scan two weeks later as "the baby might be too big."
Two weeks later the scan showed all the above plus two weeks. The verdict was "oh that's all fine." 
I realise now that they were probably worried about diabetes but at the time my focus was on the birth and I couldn't get my head round how at 34 weeks I had a "too-big" baby but at 36 weeks it had grown proportionally but was suddenly no cause for concern.
Any mention I made of a caesarean due to the big baby "they" had alerted me to and consequently scared me shitless about was contemptuously brushed aside.
DS1 was a caesarean after 24 hours labour due to failure to progress, probably due to his massive head not engaging, even in labour I think - it was too high to get a blood sample from just before they did the section. (The lack of engagement in this first LARGE baby with very big head also having been contemptuously brushed aside.) He was 9 lb 9 oz; the biggest baby I had ever heard of in my social circle at the time, but that was a few years ago - I have encountered bigger since, born naturally too!
At the rate of a baby gaining half a pound a week and losing a bit after term, the 6lb 13oz at 34 weeks was right on target - I would estimate he should have been 9lb 13oz at term and was nearly 2 weeks late so the 5oz lost fits.
A friend at the same hospital had a section suggested as her baby was "so big" - turned out to be 7.5 lbs. Could never understand why no one suggested an elective for mine when I thought all the signs were there. But we were both fine in the end, so no big thing for us I guess.