When I was pregnant with my (only) child, I enjoyed going out to bars, seeing live music, spending time with my friends, thinking and talking about stuff besides my big belly... It made me feel sort of not-pregnant -- like a smart, fun, normal, rational, adult again.
Granted, these bars weren't smoky, weren't too loud, and no one I went out with was getting drunk. (Intoxication isn't the only reason for going to bars!) Also, I couldn't stay out as late as I'd been able to pre-pregnancy, but I knew it would be a while before I'd have such unfettered freedom (like, 10 years and counting...). The people who invited me out were definitely friends, not "friends."
What was interesting to me was the looks and occasional comments I got from other people. I also got the same reactions from people when I chose to stand on the subway (I had an 8-5 office job at the time), run in the park, and take the stairs at work.
Despite Schuylercat's statement about the state of pregnant women's emotions (and boy, do I feel bad for him and the mother(s) of his kids!), some women do just fine during pregnancy -- enjoying working, playing, exercising, even having sex -- right up until they go into labor. I found it tedious to focus on being pregnant all the time, and was happy to have any opportunity not to.
Just my healthy, happy $0.02.
:-D