What causes a head to be soft when it is first born?

The skull of a newborn baby is not completely ossified, meaning that it is not fully hardened into bone. Instead, it is made up of a series of soft, flexible plates that are separated by sutures, which are fibrous joints. This allows the baby's head to mold and change shape as it passes through the birth canal.

After birth, the baby's skull continues to grow and develop. The plates of bone gradually fuse together, and the sutures close up. By the time the child is about 2 years old, the skull is completely ossified.

The softness of a newborn baby's head is important for several reasons. It allows the baby's head to mold and change shape as it passes through the birth canal, which helps to reduce the risk of injury to the baby and the mother. It also allows the baby's brain to grow and develop rapidly.

In addition, the softness of a newborn baby's head can be used to assess the baby's health. For example, a soft spot on the baby's head may be a sign of dehydration, while a hard spot may be a sign of a skull fracture.