Burping Face Down

Part of our obsession with getting our girls to burp is because this month they started to occasionally spit up large amounts. It doesn't seem to upset them, but they'll bring up what seems like two or three ounces of milk. It's quite disconcerting. We've given up on the burping technique where you lean the baby forward from a sitting position -- it crunches their stomach too much and triggers the spit up. This face-down position seems to work okay though. The best position is still over the shoulder though.