Anything that strengthens the pelvic floor and can be done safely during pregnancy - or exercises done in positions that help keep baby in ideal birthing positions. Hands and knees, squats, etc. Of course be mindful of intensity as anything to intense can be harmful.

You may want to look into things like pelvic tilts, too. This website link might give you some ideas, just watch as some of them are only ideal for women with breech babies, but the majority are ideal for all moms to be. They're not exercises per-say but might give you an idea for exercises you can do that put moms in good positions.

Lots of stretching, I was so so so sore when I was pregnant, stretching helped a lot, just watch as some mamas become hyperflexible once everything lets go so they can often go a bit further than they should so nothing too big. less