My sister had a bub on the weekend she was told at her 36 week scan her baby was small (6lb which well isnt overly small really i guess thats just to me though)
At her 39 week scan she was told he was 6lb8oz She had him three days later and he was 8lb9
Maybe they are more so just a guideline but i had same experience with my last bubs and so did freind