Flat head

M
Anyone else's Pediatrician tell them their baby's head is slightly flat in a certain area? My pedi told me my baby has a little flattening on the right side which makes sense because he prefers to sleep with his head turned that way. Anyone have any ideas to get him to sleep with his head to the left? I thought about putting a blanket under his head so he turns one way but I'm a little worried about him turning into the blanket to sleep anyway. Any ideas would be appreciated!