At 38 weeks they estimated my baby to be 7lbs 5oz. I was 4 days overdue and he was 10lbs 8oz.
With my last they did u/s 6 days before my c section and said 7lbs 14oz and she was born weighing 8lbs 1oz so if u factor in average weight gain of baby in the last few weeks they were right
It can be off one or more pounds. It's not the most accurate thing. They told me at 35 weeks that my daughter was already 8 lbs... she was born at exactly 40 weeks at 7 lbs and 5 ounces