Congenital malformations in 10,000 consecutive births in a university hospital: need for genetic counseling and prenatal diagnosis.

Ten thousand children born consecutively in a university hospital were surveyed for the presence of major congenital malformations. About 2% (174) had a major congenital defect. Seventy-eight percent (135 of 174) of these malformations are associated with increased recurrence risk (greater than 1%), and 9% carry a high recurrence risk (greater than or equal to 10%). On the basis of the recurrence risk of 1% or higher and the feasibility of prenatal diagnosis, such a procedure should be considered in future pregnancies in 45% (79 of 174) of the mothers, especially inasmuch as 40% were primiparae younger than 36 years.