tenar,

these scans can and more accurately usually are very out in the estimates!! If I can offer one piece of advice about this ....forget about it! A friend of mine had her baby on monday morning, she was 40w on the sunday. She had a growth scan at 36weeks and was told her baby would be AT LEAST 9 and a half pounds but more around 10 or 11 pounds, she was induced because of this, luckily she was given the gels and had a quick labour without the need for the drip or any other forms of intervention but turns out bub was 8pd 11!! Not huge