i have bpd also, and having it didnt affect my choice to have kids. my daughter, the oldest, is only 3 so it wont show up for years if she does have it, but my mom has said there were signs when i was young (isolating, overly-emotional) that i havent seen in her. honestly, stressing about is bad for the baby, who certainly feels when you are all worried. so relax and enjoy this exciting time! :)
It is more likely that he will have it, but it is in no way a slam dunk. From what I've seen is one parent with bipolar is a 10% - 25% chance depending on what studies you look at. So it is more likely he won't have bipolar which is positive news. And if he does end up with bipolar there will be 18 years more research and they will have far superior treatments.