Some BH can be painful - my DW has had some quite painful ones. It can be hard to tell the difference.

I was reading on wikipedia the other day that women can be "distracted" from BH by exercising. Perhaps you could try a quick jog around the block and see how things go?

(Disclaimer: the above was meant as a joke. As the partner of a 39 and a half week pregnant woman, I in no way endorse jogging as a way of differentiating between BH and contractions.)