An approach to the estimation of the true number of congenital malformations

Vital statistics reports of congenital malformations are of widely varying quality and completeness. They remain, however, the major data source for population studies of birth defects. The Environmental Surveillance Center of the University of Missouri in using birth defects as a measure of possible environmentally caused health effects required an estimate of the true number of such defects occurring in a particular place during a specified time. This article presents a method for making such an estimate and is based upon the matching of birth certificate reports describing birth defects and infant death certificates. The reasonable assumption is made that the death rate among the children with known birth defects is the same as the death rate among all infants with congenital anomalies. The estimated rates using this method closely resemble those rates obtained in hospital record studies.