Survival Rates of Infants With Birth Weights Between 501 and 1,000 g: Improvement by Excluding Certain Categories of Cases

• Reported survival rates of infants with birth weights under 1,001 g vary greatly; by implication, high survival rates may be used as a measure of the standard of perinatal care. To illustrate the importance of precisely defining the population sample, we determined the survival rate to 2 years of 238 infants with birth weights of 501 to 1,000 g, born between 1977 and 1980. The rate was 33.6%; however, by excluding certain categories of patients, the survival rate was augmented to 46.9%. There were 36 infants who died in the delivery room and an additional 34 who died before the age of 3 hours in the intensive care unit; together they contributed 29.4% to the total mortality of 66.4%. This group is especially liable to influence reported survival rates. Although exclusion of patients is legitimate, the criteria need to be precisely defined if data between centers are to be compared. ( AJDC 1985;139:470-471)