As far as travelling as a passenger while pregnant, an airline will allow it up to seven days prior to your due date.
As a required crew member at AA/Eagle you may not fly (as a pilot or F/A) during your last 12 weeks. I don't remember of-hand what the rule was for the timeframe after delivery, I'd have to dig out my books & look it up. I only ran into a handful of women who actually worked up to the last 12 weeks. By then you're so tired, starting to get big, and will usually have jumped at the chance to bail early by then.
As a GA pilot I don't believe there are any restrictions, it would be up to the individual to decide when 'enough is enough'. Also when you're ready to fly again after delivery. I had my medical (3rd class) done at 5 weeks post-partum last year, the doc had no issues with anything. He just asked if there were any complications and how was I feeling. My medical had expired while I was pregnant, and I knew I wasn't going to be operating any aircraft any time soon, it would have been silly to have renewed it.
Basically just be smart, if you feel like it's time for you to go on leave. Go. Don't push it. GA or airline, airplanes will be there for you to fly when you've recovered. When I was 7 months with our first, we were going to go to FL, my doc actually encouraged me to go. He said to take advantage of the opportunity to get away before baby arrives. I had a totally complication-free pregnancy, and there was no reason not to go. I ended up not going because of loads, but it was nice to know that I could!
