Those ultrasound weights can be pretty off. They told my sister in law she was going to have a large baby because she had gestational diabetes,so they induced her early because of their concerns about the baby's large size,she ended up being only 7lbs 7oz and 19 inches long. My last baby was 8lbs 10 oz,she was a c-section but so was my first, but i was told larger babies are easier to push out.Try not to worry too much about the the ultra sound weight says, they told me 3 weeks before her birth that she was close to 10lbs and possibly bigger, but she ended up only being 8lbs 10z and 21 inches long.