These soft spots are spaces between the bones of the skull where bone formation isn't complete. This allows the skull to be molded during birth. The smaller spot at the back usually closes by age 2 to 3 months. The larger spot toward the front often closes around age 18 months.

What happens if fontanelle doesn't close?

Soft spot that doesn't close

If the soft spot stays big or doesn't close after about a year, it is sometimes a sign of a genetic condition such as congenital hypothyroidism.

At what age do cranial sutures close?

At birth, the sutures decrease in size (molding) and allow the skull to become smaller. In children, the suture enables the skull to expand with the rapidly growing brain. The suture will close and fuse around age 24.