The quality of notification of congenital malformations.

The United Kingdom Congenital Malformations Notification Scheme began in 1964. It is based on notes added to birth notification forms. In Birmingham, a local scheme based on multiple sources has been run in parallel for the last 20 years. The national notification scheme records malformations noted up to the age of 7 days, whereas the Birmingham scheme collects information up to the age of 5 years. A case by case record linkage of the two registers was carried out. This operation revealed the essential completeness of the multiple-source register but gross defects among notifications. The extent and nature of the deficiencies are described. They include defects of ascertainment of malformed infants and of major additional malformations in those infants who are in fact notified, overnotification of infants without significant malformations, and misclassification of the major malformations that were, in fact, notified. The defects arise partly from the defective design of the national scheme and partly from defective implementation and a lack of designated supervisory responsibilities. The main requirements for a scheme that could indeed be relied upon to meet its monitoring objectives are set out.