I walk 5-6 days a week and do a yoga class once a week. Occasionally I'll add in some light weights for upper body but that's about all I can handle while I'm pregnant. I couldn't do anything for the first 4 months so I'm making up for now while I can :-) I think I might start swimming on weekends in the next month or so because my belly is getting huuuge and it's getting hotter here in Oz!
Going on walks is really good!
I have a birthing book that has dif things you can do to help your body get ready for labor while also staying in shape its called your pregnancy and childbirth it has lots of interesting stuff in it. Also I go swimming four times a week minimum and spend thirty mins to an hour in the pool.