Delayed closure of fontanelle is most often due to malnutrition, rickets, and hypothyroidism. These can affect the normal growth and development of the skeleton, leading to delayed development and thus delayed closure of fontanelle. In malnourished children, the lack of calcium intake prevents the cranial sutures from closing properly, resulting in delayed fontanelle closure; in children with rickets, the lack of vitamin D prevents the effective absorption of calcium and prevents the cranial sutures from closing; and in children with hypothyroidism, the lack of thyroid hormones prevents normal development. In addition, it may also be seen in cranial clavicle dysplasia. So, what tests can be done to confirm the diagnosis of delayed fontanel closure in infants? The following are the tests for delayed closure of infant fontanelle: 1. Cranial x-rays show enlargement of the cranial cavity, thinning of the skull and separation of the cranial sutures, and delayed closure of the anterior and posterior fontanelles. 2.Ventricular gas or water-soluble iodine contrast can show the morphology and size of the ventricular system and the thickness of the cerebral cortex. 3.Two-dimensional ultrasonography of the head shows no displacement of the midline brain waves and enlargement of the ventricular system. 4.CT or MRI scans see a marked enlargement of the ventricular system, and sometimes the cause of hydrocephalus can be detected. The closing time of fontanelle is closely related to the child itself. Some babies are born with larger fontanels and may close later; on the contrary, some babies are born with smaller fontanels and may close earlier. Due to individual differences, the general principle for the closing time of fontanelle is that if the baby is in good spirits, has normal motor and growth development, and has normal intelligence, parents need not be too nervous about the early or late closing time.