The tip of the iceberg: a validation study of the Victorian Congenital Malformations/Birth Defects Register.

Among 1500 children under 4 years of age admitted consecutively to two paediatric teaching hospitals in Victoria in 1985 the prevalence of birth defects was 20%. Fewer than half of these defects had been notified to the Victorian Congenital Malformations Register. Only chromosomal anomalies and, to a lesser extent, major structural malformations present at birth were adequately ascertained. The implications for birth defects monitoring and for service planning are discussed.