My only u/s booked when I was PG with Matilda was the 18-20week scan, but because we had a m/c scare we did one at 9 weeks as well. This time around I had to ask for a 12 week scan even though the midwives & my GP have tried to talk me out of it saying it won't serve any purpose... so we are still deciding if its worth going to it. As long as I can hear the hb on doppler I will be happy.