Since you can't go anywhere, you can try stairs. When I'm stuck at work overnight or longer, I walk (very quickly) up and down the same flight of stairs for an hour. Good music is a must cuz it can get pretty boring. It is an amazing quad and calf work out. I use a heart monitor to make sure I don't get lazy. It's too easy to slow down on the way up. You'll get your heart rate up as high as you want for sure! I usually maintain a HR of 150 if the music is lively. There is also very little bumping up and down since you aren't actually running. That means it's gentler for the uterus and less likely to start bleeding.

When i was breast feeding and post partum I also did jump rope which is alot of bumping up and down, but I started that after 6 weeks. Again, amazingly tough workout but you're right there for when the baby cries.