Craniosynostosis is a birth defect that occurs when the sutures, or growth seams, in a baby's skull fuse too early, causing abnormal head shape and potentially restricting brain growth. Causes and effects: The fibrous sutures in a young infant's skull prematurely turn into bone, altering the skull's growth pattern. If multiple sutures close too early, the brain may not have enough room to grow, which can increase pressure on the brain.

https://www.alderhey.nhs.uk/services/craniofacial/