TRENDS IN MORTALITY AND CEREBRAL-PALSY IN A GEOGRAPHICALLY BASED COHORT OF VERY-LOW-BIRTH-WEIGHT NEONATES BORN BETWEEN 1982 TO 1994

Objective. To analyze whether the increasing survival of very low birt h weight infants during the 1980s and 1990s has increased the risk of cerebral palsy among survivors. Methods. The study cohort consisted of 2076 consecutively born infants, with birth weights of 500 to 1500 g and no major anomaly, born July 1, 1982, through June 30, 1994, to res idents of a 17-county region in North Carolina. These infants had a me an birth weight of 1096 g (standard deviation, 251 g) and a mean gesta tional age of 29 weeks (standard deviation, 3 weeks). One thousand fiv e hundred sixty-eight infants (76%) survived to 1 year adjusted age, a t which point 1282 infants (82%) were examined at our medical center. The diagnosis of cerebral palsy was made only if the examining pediatr ician and a pediatric physical therapist agreed on the diagnosis. To a nalyze trends across time, the Cochran-Armitage chi(2) test and logist ic regression were applied to data for infants categorized into six 2- year epochs according to year of birth. Results. Mortality did not cha nge significantly through 1990, and then began to decrease in 1990 to 1994. During the study period, mortality decreased from 36.8% between 1982 and 1984, to 13.8% between 1992 and 1994. The prevalence of cereb ral palsy among survivors was constant from 1982 to 1988 (11.3%), decr eased slightly from 1988 to 1990 (9.2%), and was lowest in 1990 to 199 4 (5.2%). These secular trends in mortality and cerebral palsy risk re mained significant when adjusted for gestational age, gender, and race . When adjusted for surfactant use, the trend in mortality was no long er significant, whereas the trend in cerebral palsy risk persisted. Co nclusions. The increasing survival of very low birth weight infants in the 1980s and 1990s has not resulted in an increased prevalence of ce rebral palsy among survivors.