Lindsey I spent a few hours on the internet doing research and then talked to an ob/gyn. After that I worked with my pregnant wife and I designed Fit Pregnancy. All exercises are safe as long as you are healthy. One thing the doctor was concerned about is when women are pregnant they can lose their balance more than normal. Always watch your balance and if possible use a spotter. Also Running is ok as long as you have been doing it before your pregnancy. Walking is suggested up until the day you deliver. My wife is dealing with gestational diabetes and we use this program along with walking to keep it in check.
I hope you have a wonderful experience and everyone is healthy throughout.
Depends on your current fitness level... i recommend keeping up with cardio workouts, and yoga