I have pelvic floor damage due to the birth of my first child. But I haven't had a second yet (not preggo either) so I can't help you there.
What I can share is this...
I have had bowel movement issues ever since Beth's birth close to 3yrs ago. I had a 4hr labor, and Bethany was in distress (cord wrapped tight on her neck and short) which necessitated emergency transport in an ambulance from the freestanding birth center across the street to an ambulance. My midwife was able to avert the automatic csection (found out the ER was ready and waiting for me) and Bethany was born VERY QUICKLY with forceps assistance (complete with episiotomy).
I tore ALOT. Nothing over a 3rd degree, but it was up, down and up both sides. They took over 45min to stitch me up. To be honest I would go through labor and delivery w/o drugs over and over again before I got stitched up again like that.
I saw my midwives at 6wks post-partum but it was still really too early to tell. At about 5mo post-partum I went to my PCP (a DO) and she told me that my bowel movement issues were due to the "pregnancy hormones still in my system since I was still nursing." I KNEW that was wrong!
I just bit the bullet and lived with it. It's not a HUGE issue....just that it's not right...if that makes sense. I need to use a lot of support to my perineum for bowel movements and some bleeding due to the stress of them. (Sorry if that is TMI). I also have almost NO internal cues any longer to indicate to me that I need to have a bowel movement....I either don't have to go or I have to go RIGHT NOW. Interestingly, I didn't have any incontinence issues until recently and they are quite minor...but increasing. Not sure why that would have changed??
When I went back for my 1yr appt I had a long talk w/ the midwife. She said there was definitely a problem and referred me to a few different places (all different paths for treatment). One was biofeedback which I didn't pursue and another was a dr. I did some more research and found this...
http://www.pelvicfloorinstitute.com/pelvic.nsf
Who would of thunk that they would have an entire INSTITUTE?? It's in a local hospital here in Philadelphia. I called and made an appt for an evaluation.
It seems that the back portion of my pelvic floor was torn during Beth's delivery and although externally it was stitched and healed, internally the muscles never healed back together. This is what is making it difficult to "push" during bowel movements. I saw a great dr ( I think she was a resident or something similar) at the PFI and she explained it all to me...very clearly too I might add.
She said that seeing as I was going to the birth center for my gyn care as well as the birth of Bethany, she could tell what my answer would probably be regarding my options

.
They could do surgery to fix it. She was VERY clear that it wasn't very invasive and would be A TON less recovery (and pain) than when I had Bethany. However, having another child (or children) vaginally would probably re-injure the pelvic floor and the surgery would have to be repeated.
She suggested that since I seemed to be doing okay, despite the damage to my pelvic floor, that I wait until after I am done having children and then return for the surgery. She didn't share any other options other than surgery at that time....not sure if it is because there aren't any or that they just don't consider it...but based on the info I have about them...it doesn't seem to be that way.
I did specifically ask her about carrying and delivering more children and she said that (at least in my case) it shouldn't be a problem. She said if there was even any minor problems carrying later in pregnancy that they could "easily" place a device under my pelvic floor for support. I can't remember the name she used for it..but it seemed like it was something easily done in office...not surgically inserted at all. The dr specifically told me that she had seen women with significantly worse damage to their pelvic floor successfully carry and deliver (vaginally).
In subsequent discussions w/ my midwive(s) they all seem to indicate that it shouldn't be an issue for a subsequent pregnancy.
My annual is due this summer and I will discuss it w/ the midwife again. I hope this helps in some way???
Christine