I had one at 8 weeks as my gp wants viability ultrasounds, one at 12 weeks because of a bleed which was thought to be a miscarraiage until baby was waving at us, one at 18 weeks for ongoing bleeding and my 20 week scan. I also had bedsie ones at 37,38 and 39 weeks to confirm breech presentation
Where I was, you got 12 and18 week ultrasounds. If you opted out of the nucal scan, you didn't get the 12 week one.
With my first daughter I also had ones at 8, 10 and 16 weeks due to bleeding which resolved itself and one at 41 weeks to check fluid levels because I was overdue.
With my second daughter, I had them at 6, 8, and 10 weeks because of bleeding which resolved itself by 12 weeks. I then had one at 33 weeks when my water broke to look at fluid levels and estimate the baby size for delivery.
With my loss I only had the 12 week scan because everything was fine.
With my first pregnancy which ended in a miscarriage at 7 weeks I had one at 6 weeks (nothing was visible) then at what would have been 9 weeks to make sure everything had been expelled.
With my second (and fully successful) pregnancy I had at 6 weeks to confirm (standard with my OB), again at 8 weeks because of the previous miscarriage, then the NT scan at 12 weeks and the anatomy scan at 20. Also had scans at 27 & 29 weeks because he sent me to L&D twice for potential preterm labor. Last one was at 38 weeks to conform position.