Congenital malformation surveillance.

Records (24,798) of the Hungarian Congenital Malformations Registry for the 728,343 total births in 1973-1976 were examined. A total of 3,116 babies were identified as having a primary congenital abnormality which may be associated with secondary developmental anomalies. Some 842 of these babies had 1,194 additional congenital abnormalities that we consider to be secondary. The exclusion of these secondary abnormalities from birth prevalence figures represents a more accurate registration and evaluation of congenital abnormalities from both statistical and etiological points of view.