Hello from a fellow fibro-sufferer
I can only respond based on my experiences with fibro and pregnancy, and everyone is different!
I was dx'd with fibromyalgia when I was 24, about 2 years after the birth of my first child. I went through the typical symptoms and reached a point where I had to hold onto the wall to support my weight while I walked (and mind you, at the time, I weighed all of 120lbs!) and I was convinced I had Alzheimers (my mother has early-onset Alzheimers - started at age 43).
I went through all of the pain meds on a regular basis, the relafen, the slew of anti-depressants, the soma twice a day, etc... and of course those lovely triggerpoint injections that caused me such horrible pain for 4 days before helping at all, it was hardly worth it!
I'm one of the lucky sufferers, however. I've found that as long as I get refreshing sleep, eat pretty well and exercise, (without overdoing it) I can live a very functional life, with the occasional bad flare up, but it's not debilitating like it was at one point. Lots of antioxidents, and less flour and sugar!!
In any case, I got pregnant with my second child in 2000 and after the first trimester, all symptoms of the fibro were gone for the duration of the pregnancy. I can't say this is typical, but I can say that it was a great relief to have relief

I still felt tired a lot, throughout the entire pregnancy, but I only had minor pain. (Compared to pregnancy #1 with sciatic problems).
I'm working on getting pregnant with #3, and I have faith that I can manage my pain throughout.
Keep in mind, my doctor told me once that he'd never met a woman with kids that wasn't diagnosed with fibromyalgia. And the drugs often end up being a crutch without helping.
I know it's hard to get up and exercise while in pain ... thinking you'll just wait another day until the pain goes away -- but drink a **lot** of water and take antioxidents, throw some lemon juice in the water and I tried DHEA to get through the worst spells. Nothing works for everyone, but Fibro is a manageable pain, once you find what works for you!
Good luck, ladies

Gentle Hugs!
Meghan