I've had 4 so far. One at 6 weeks, one at 8, a 16 week gender scan, and a 20 week anatomy scan. I'm having another at my next appointment because we couldn't get a pic of the left ventrical at the anatomy scan. Then I'm having a 3D/4d ultrasound at 30 weeks. So I'll have 6 total. My friend that was high risk had one every 2 weeks since 10 weeks.
Ive only had 2. Was planning on a 3rd for a 3d ultrasound.
Ultrasounds so far seem safe. Ultrasound does cause vibration of cells so we don't know if it does anything to DNA. Some people avoid them. But there's no evidence so far that they cause any harm.
Ultrasounds are perfectly safe.
Ultrasounds are safe during pregnancy. I had 5 or 6 with my first child, because she was breech. So they kept checking to see if she turned. She is was fine. It is recommended to only have then when needed though.