Heterogeneity and recurrence risk for congenital hydrocephalus (ventriculomegaly): a prospective study.

We report on 261 prospectively ascertained pregnancies studied to determine the recurrence risk of congenital hydrocephalus. Our results suggest that couples who have had one previous child with hydrocephalus have a recurrence risk of 4%. Such couples should be offered prenatal diagnosis in the second trimester of all subsequent pregnancies. It is suggested that, apart from the X-linked recessive cases, ventriculomegaly is mostly multifactorially determined.