Experts at Princeton University and the Brookings Institute demonstrate with this new data how the human element plays a major role in the effectiveness of different birth control methods. Here as presented by The New York Times in their article: How Likely Is It That Birth Control Could Let You Down? – thank you!

For popular methods like the condom, it is clearly the users who destroy the effectiveness. Coming out on top again, as usual, the IUD as the best method for reversible protection.