Congenital hydrocephalus is where hydrocephalus is present at birth. It is caused by a variety of factors, such as genetic abnormalities, infections, or brain malformations during fetal development.

The most common cause of congenital hydrocephalus is obstruction of the cerebral aqueduct — the long, narrow passageway between the third and fourth ventricle or cavity of the brain. Congenital hydrocephalus may result from a blockage, infection, hemorrhage, tumor or arachnoid cyst. It may also be caused by genetic abnormalities or developmental disorders such as spina bifida and encephalocele. Congenital hydrocephalus can lead to developmental delays, intellectual disabilities, and neurological deficits if not treated promptly.