What is the effect of fetal skull being fused at birth?

The fetal skull is not completely fused at birth. The bones of the skull are connected by fibrous joints called sutures. These sutures allow the skull to grow and accommodate the growing brain of a newborn. At birth the skull consist of several bones separated by fontanelles or soft spot. As a child grows the spaces begin to close (ossification) and by early adulthood, all the fontanelles have completely ossified or closed up, fusing together to form a solid skull.

If the fetal skull were completely fused at birth, it would not be able to grow and the brain would be unable to develop properly. This condition is known as craniosynostosis and can lead to serious health problems, including intellectual disability, vision problems, and hearing loss.