OB plus an outside high risk specialist?

Debbie
Hi everyone, after my first trimester with my fertility specialist I had my first visit with an OB who's office says they specialize in high risk pregnancies. However, She said that at 29 weeks I would be seen be a high risk specialist that they contract outside of their office every week. Is this normal, to be seen by someone else other than your OB? Or are there OB's who can take care of seeing you every week without outsourcing you?