This study was designed to analyze whether increasing survival of VLBW infants during the 1980's and 1990's has increased risk of CP among survivors. The study cohort consisted of 2076 consecutively born infants, with birth weight 500 to 1500 gms and no major anomaly, born 7/1/82 - 6/30/94 to a resident of a 17-county region in North Carolina. 199 infants (10%) were lost to follow-up. At one year of age, 1282 (94%) of the 1369 surviving infants were examined at our medical center. The diagnosis of CP was made only if the examining pediatrician and a pediatric physical therapist agreed on the diagnosis. To analyze trends across time we categorized infants into six two-year epochs according to year of birth, and applied the Cochran-Armitage X2 to 2 × 6 tables for the binary outcomes of CP and mortality. In the Table “healthy” refers to survival without CP; “CP rate”, to the number of CP cases /100 live births; and “CP risk”, to the number of CP cases /100 survivors. Mortality was fairly constant through 1990 and then began to decrease in 1990-94 [p < 0.001]. The risk of CP was constant from 1982 to 1988, decreased slightly 1988-90, and was lowest in 1990-94 [p = 0.003]. These secular trends in mortality and CP risk remained significant when adjusting for birth weight, gestational age, and gender. Thus, the increasing survival of VLBW infants in the 1980's and 1990's has not resulted in an increased risk of CP among survivors.

Table 1
Full size table