Here's an article in today's New York Times that confirms what I suspected when I was pregnant: the medical establishment has no real clue about how much & what kind of exercise is safe during pregnancy, so doctors tend to give arbitrary advice (often framed as Fact) that errs on the side of conservatism. Here's the full story:
FWIW, I continued to lift through my pregnancy, up to about the beginning of month 8. At that point, my belly just got too unwieldy, so I shifted to moderate cardio 3-4 times a week. By the very end, this had tapered off to light cardio.
I credit exercise w/ giving me the strength for a completely natural child birth, and for speeding my recovery and fat loss post-partum. Of course, it could have been something else instead -- that's the nature of anecdotal evidence!
Kim

She also talks about weight gain during prenancy, and how women tend to go overboard with the whole "eating for two" thing.
Your abs of steel are totally a motivation for me. I don't know if I want to have abs that defined, but something close would be nice! And if you can look that ripped after having a kid and being close to 40, damnit, I can, too!