For the vast majority of children, the fontanelle closes at 18 months after birth. If the fontanelle closes early or is significantly delayed in children, it is mostly due to pathological causes. If a child’s fontanelle closes too early, it is mostly due to a cerebellar malformation or poor brain development. If the closure of fontanelle is significantly delayed, especially if it does not close after the age of 2 weeks, it should be considered to be caused by encephalitis, hydrocephalus or brain tumor, and timely intervention is needed. If the fontanelle closure is delayed due to hydrocephalus, the child should undergo surgery.