More detailed content to come in Q4 of 2022, but essentially, it depends.
First and foremost, unless your obstetrician has a phenomenal reason for doing so, you should not ‘just plan on a cesarean section’ if you have hardware somewhere in your pelvis. We can’t assume that attempts at vaginal delivery will fail. But we can’t promise it will work, either.
Here’s the 411:
Because the sacrum won’t be able to move as much, relaxing your pelvic and abdominal muscles is even more important for you than someone without hardware in their pelvis. Having ‘as much low back mobility and motor control’ as possible is important, as is making sure that the coccyx (tailbone) is free to extend during delivery, to open the outlet however we can. (pillow under one side of pelvis, making sure your tailbone is free to move and not crammed against a stiff mattress–pictures and vids to com in future).
So in general, talk to your OB. Vaginal delivery might be fine. Or it might not be. You may potentially have a slightly higher chance of Cesarean Delivery than someone with a non-fixated pelvis…but only slightly. So delivery in a hospital setting, where you have the resources for C-section available to you, is prudent, if that route is needed.
Remember, labor and delivery is complicated in the best of times. Do your best. Hope for the best, prepare for the worst, and be at peace with whatever happens. You are doing your best and I am proud of you!