Jols, I had an anterior placenta, and DS was firmly posterior for some weeks before the birth, and didn't turn when being born. But he was pretty badly malpositioned, with his head wedged in my pelvic cavity, .

I'm no expert, but I seem to recall 'reading' that you have a slighty increased chance of having a posterior bub if you have an anterior placenta. But I wouldn't worry about it! And hang out on Spinning Babies if you're concerned down the track!