35 week growth scan update

35 week growth scan update

So the last growth scan we had since we were measuring behind 3 to 4 weeks was at 28 weeks and baby boy was 3 lbs. 3 oz and they said that he was in the 58 percentile. Today at 35 weeks he is measuring 5.6lbs. and they said that he's in the 31st percentile. He is head down and perfect! Everything that I've read says that an average 35 week baby is 4 to 6 lbs. So how is thay only the 31st percentile? confused????. Anyway he is healthy so I am happy. What do you ladies think of this info?