SURVIVAL AND DEVELOPMENTAL DISABILITY IN INFANTS WITH BIRTH WEIGHTS OF 501 TO 800 GRAMS, BORN BETWEEN 1979 AND 1994

Objective. Because the survival rate has increased for extremely low b irth weight neonates, many have raised the concern that the rate of de velopmental disability among survivors will also increase. To address this concern, we analyzed changes over time in survival and major neur osensory impairment in a sample of extremely low birth weight infants born between July 1, 1979, and June 30, 1994. Methods. The study sampl e included 513 infants with birth weights of 501 to 800 g who were car ed for in either of the two neonatal intensive care units that serve a 17-county region in northwest North Carolina and who were born to mot hers residing in that region. At 1 year of age (corrected for gestatio n), survivors were examined by a pediatrician and were tested using th e Bayley Scales of Infant Development. Major neurosensory impairment w as defined as cerebral palsy, a Bayley Mental Developmental Index <68, or blindness. A total of 209/216 (97%) of survivors were examined at 1 year of age. Epoch of birth was defined as follows: epoch 1, July 1, 1979 to June 30, 1984; epoch 5 July 1, 1984 to June 30, 1989; and epo ch 3, July 1, 1989 to June 30, 1994. Results. Survival rates for epoch s 1, 2 and 3 were, respectively, 24/120 (20%), 63/175 (36%), and 129/2 18 (59%). In contrast, the proportions with a major neurosensory impai rment did not increase over time; rates for successive epochs were 6/2 4 (25%), 17/61 (28%), and 26/124 (21%). Rates of cerebral palsy were 3 /24 (13%), 12/61 (20%), and 9/124 (7%); rates of delayed mental develo pment were 4/24 (17%), 12/61 (20%), and 17/124 (14%); and rates of bli ndness were 2/24 (8%), 0/62, and 5/124 (4%), respectively. Conclusions . This analysis suggests that the increasing survival of extremely low birth weight neonates since the late 1970s has not resulted in an inc reased rate of age.