Can you become pregnant while taking the birth control pill?

Nothing is 100% effective in preventing pregnancy aside from abstinence and radical surgery.

Used pretty much right, Birth Control methods (apart from surgery) are rated at about 98-99+% effective.

It's to the point where failures(=pregnancies) are difficult to investigate fully.

Maybe a condom was nicked by a sharp nail or jewelry, maybe a stomach upset caused someone to lose the pill before it'd been absorbed by the body, Etc Etc.