Objective: To assess changes in survival and disability in liveborn extremely low birthweight infants (500-999 g) in Western Australia, 1980-1987.
Design: Cohort study comparing two periods, 1980-1983 (P1) and 1984-1987 (P2).
Participants: All 586 liveborn extremely low birthweight infants in WA in 1980-1987 (266 in P1, 320 in P2).
Main variables examined: Birthweight, place of birth, age at death, neurosensory examination findings and scores on the Griffiths Mental Development Scales or other standardised test results.
Results: 482/586 infants (82%) were born at King Edward Memorial Hospital (KEMH), a level III referral centre, and a further 4% were transferred there after birth. The proportion born at KEMH increased from 78% in P1 to 86% in P2. Survival increased from 35% to 43% overall. In those below 800 g birthweight, survival doubled from 14% to 29%. There was no change in the age at death for non-survivors. Follow-up information was known for 222 of the 229 survivors at median ages of 46 months (P1) and 43 months (P2). Disability rates in infants below 800 g birthweight remained static (P1, 26%; P2, 28%), but fell in those of 800-999 g birthweight from 24% to 13%. Overall, survival free of disability increased from 26% to 34%.
Conclusion: Increased survival rates occurred without any increase in the rate or severity of disability in survivors.