31w6d and ar my appt yesterday he didnt do exact measurements because he had 2 weeks ago but he said my lo is about 3.75 lbs.
I'm 31 weeks and my little girl is 1.51kgs my doc says that is good as she will double in weight in the next few weeks
I had an ultrasound at 31 weeks and was told baby was 3lbs 15ozs.
My ultrasound was when I was exactly 32 weeks and my girl was 4.5 lbs, which is average, so yours is just a little over average for 31 weeks, which is good!