Hmmm, my SIL was always being freaked out about how big her baby would be, even at 20 weeks she was told he was 'above average'. At 34 weeks they told her they were worried that bub was too big to come out naturally (TOTALLY freaked her out). Anyhoo, bub ended up being born 4 weeks early and only weighed 2.6 kg. He was really long though!
With my DS I was also always told bub was 'above' average. I had him at 38 weeks and he was already 3.5 kg, so yes he was big.