After birth, if a child’s fontanelle closes prematurely, it may affect brain development and health. The timing of fontanelle closure is crucial; closing before six months may lead to microcephaly or poor brain development; after 18 months, it’s too late. Early closure may be associated with conditions such as hydrocephalus, rickets, and dementia. A bulging fontanelle may indicate increased intracranial pressure, potentially leading to meningitis, encephalitis, and vitamin A toxicity.