Ehh, I was always torn about this. It's really no secret that Mark originally wanted Brooke to have this abortion SL and gave us hints to that in the S3 finale but then the CW didn't allow him to do it.
On the one hand, Brooke aborting a baby would mean NH wouldn't have Jamie and I wouldn't actually mind that because Haley's pregnancy was completely overshadowed and it was way too soon for NH to have a baby (although I don't know if I can say if anything's too soon for a couple who gets married in HS...) so Brooke aborting = no NH baby. And I wouldn't have minded that at all.
But on the other hand, I doubt Mark and/or Sophia could handle and deliver such a controversial and "heavy" storyline. And Brooke's character would've been destroyed but then again S4 destroyed her either way so I guess that wouldn't matter much.
But at the end of the day, if I could go back in time, I wouldn't have changed a thing.