The incidence of babies with irregular head shape such as a flattened section of the back of the skull have increased n the U.S. since the Back to Sleep Campaign was introduced.
That was in an attempt to prevent sudden infant death syndrome.
Doctors say timing is crucial when it comes to treatment.
It must take place while the skull is still growing and before the bones have fused and soft spots close. Repositioning involves supervised tummy time for babies when they're awake or showing them toys and encouraging them to turn to either side.
It that doesn't work Mayo Clinic researchers say helmeting therapy can help skull bones grow in the proper direction.