This is caused by either the infant sleeping with their head in the same position or a problem with tight neck muscles called "torticollis
". Luckily, both of these improve with age and can be treated non-surgically with repositioning of the head during sleep
and stretching of the neck muscles if torticollis is the problem.
If the flattening is severe, but caused by positional plagiocephaly, occasionally parents will opt for reshaping helmets for cosmetic purposes.
Craniosynostosis is a condition where the soft growth areas of the skull fuse prematurely causing a misshapen head and sometimes impeding proper brain growth. This condition is more serious and requires surgery. The consultant should be able to tell what your child has and will advise you accordingly.
Legal disclaimer: I am providing this general and basic information as a public service and my response to this question does not constitute a doctor-patient relationship. For any additional information, advice, or specific concerns, please speak with your own physician. The information provided is current as of the date of the answer entry.