Answers (1)
You should try to avoid activities that call for jumping, jarring motions or quick changes in direction that might strain your joints and cause injury. You should avoid activities where there is a risk of hard falls, or where you might be thrown off balance. Falling, even from a low height, can result in a miscarriage of the baby. Strenuous activities, or those that involve a decrease in your oxygen levels, such as hiking, are also best avoided while pregnant.
If you're healthly and in good shape, you can (and should) continue to exercise, go for walks and stay in shape.
It's difficult to say exactly how many weeks you should stop cheering but in general, the higher-risk, more strenuous activity should be stopped as soon as possible.
http://www.nhs.uk/chq/Pages/930.aspx?CategoryID=54&SubCategoryID=131
http://www.nehb.ie/nehb/services/healthpromotion/.../physicalactivity1.pdf [pdf]