Pregnancy work out videos

Does anyone have any pregnancy workout videos they'd recommend. Looking for something for each trimester. I'm an on and off active person, I'll go months working out regularly then I get lazy again. I've been lazy for a while partly bc of crazy hours at work, but I'm in ok shape. I want to feel healthy in pregnancy and I've read that exercising can also make delivery a bit easier, and the obvious - not gain as much weight. Plus I have back issues so I want to keep those under control. I'm 7 weeks pregnant now. Thanks!