Anterior placenta does give you a higher chance of baby occupying a posterior position which can cause back labour. (Check out Gardberg's study in 1994). Babies are thought to like to face the placenta. It doesn't mean you will definitely have back labour though, just chances are increased. You can do things to help baby turn though. I had anterior placenta with DD and she was back to back from 34 weeks to 38 weeks, but after 4 weeks of doing recommended exercises and not reclining she shifted to an easier birthing position.
I did a lot of research on it in my first pregnancy as I was very scared of back labour after witnessing my best friend go through it!