do not move just for babies

On the advice of our osteopath we bought the Babydorm cushion for our child with a flat back of the head. As long as the child moves is not all OK in the night but our child has an urge to move and is so slipped off the pillow that it has been lying with the back of his head on the very solid bridge for the neck area. This has happened a few nights, so the back of his head has formed a proper notch. This is because even now, after we no longer use the cushion for several months, yet. The pillow was actually counterproductive, which has now also confirmed our pediatrician.
The cushion is therefore only suitable for babies who are absolutely silent at night (there's that?).