Originated From Pregnancy.org
Here are two web sites that answer your question.
http://www.babyhopes.com/articles/depoprovera.html
http://www.americanpregnancy.org/preventingpregnancy/depoprovera.html
There have been people who have gotten pregnant on Depo. It's so hard to tell with that shot because everyone I know either bleeds the whole time or never has a period at all!
Other people asked questions on similar topics, check out the answers they received:
Other people asked questions on various topics, and are still waiting for answer. Would be great if you can take a sec and answer them