Exercise and Pregnancy

I have heard how important exercise during pregnancy is and am currently doing some research on this. I found some great information about this at Childbirth.org. They give the following guidelines (I hope this information is handy).

As, for myself, I have found that I am doing a lot more house work. My wife is extremely tired leaving me with added responsibilities around the house. Between staying caught up at work, a class I am taking and housework there does not seem to be enough time in the day. I need to make sure to take time to exercise. Any suggestions for finding this balance?