How often did you get an u/s in 2nd/3rd Tri?

Native+Girl

For mobile users: How often did you get an u/s in 2nd/3rd Tri?

My mom really wants to go with me to an u/s to see the baby. She didn't get a chance to go when SIL was pregnant so I really want her to have that experience. The problem is, I don't know at what appts I'll be having u/s from here on out so I don't know when to tell her to come. I *think* I'll have them for all my MFM appointments, but I didn't have one at my last OB appt, which I think is normal, so I have no clue what to expect there.

So how often did you get an u/s in the 2nd and 3rd Tri, with an OB or MFM?