I had my 20 week ultrasound and everything was right on track. Except the legs which were 2 weeks ahead of schedule and I expected as it happened with my little girl. (my husband is 6'2) However, at 30 weeks my baby boy's head and arms are measuring at 33 weeks? Am I going to have a big baby or perhaps deliver early? I'm nervous about the size and weight. My little girl was 7lb.7oz and 21 and 1/2 inches long.