Neonatal hydrocephalus is caused by excessive production of cerebral crest fluid or impaired circulation and absorption, resulting in stasis of cerebral crest fluid in the ventricular system or subarachnoid space, which grows and increases in pressure and enlarges the ventricles. Congenital malformations: such as stenosis of the midbrain aqueduct, diaphragm formation or atresia, atresia malformation of the interventricular foramen (median foramen of the fourth ventricle or lateral hollow atresia), cerebrovascular malformation, cristae fissure, and submicrocephalic tonsillar herniation. Infection: Fetal intrauterine infections such as various viral, protozoal and syphilitic spirochete infectious meningitis are not controlled early, and the proliferating fibrous tissues block the circulatory orifices of the cerebral crest fluid, or fetal intracranial inflammation may also occlude the cerebral pool, subarachnoid space and arachnoid granule adhesions. Hemorrhage: fibrous hyperplasia caused by intracranial hemorrhage, malabsorption of intracranial hemorrhage from birth injury, etc. Tumors: can obstruct any part of the cerebral crest fluid circulation, more commonly seen near the fourth ventricle, or choroid plexus papillomas. Others: certain hereditary metabolic diseases, perinatal and neonatal asphyxia, severe vitamin A deficiency, etc.