We are APs and made several trips to DLR and one trip to WDW while I was pregnant with my DS. At DL you should avoid the mountains and Star Tours, but that is about it unless you have other rides that bother you, such as the fact that I don't do spinny rides.
At DCA you should skip Screamin', MM, ToT, but I rode Soarin' up until about my 7th month.
Pace yourself, stay well hydrated and well fed (it's a great excuse to try all the DLR snacks that you want), and make sure to take a belly shot in front of the castle or with Mickey, or whatever it is that would be sentimental to you!
I also bought my DS's first set of mouse ears and got both his in uetero nickname (purchased at WDW before we knew whether we were having a boy or a girl) and then another set with his name embroidered on them from DL!
Have fun and congratulations!!!