Improved outcome into the 1990s for infants weighing 500-999 g at birth. The Victorian Infant Collaborative Study Group.

AIMS To compare the survival and sensorineural disability rates in extremely low birthweight (ELBW) (500-999 g) infants born in 1991-2 with ELBW babies born in 1979-80 and 1985-7, and with normal birthweight infants born in the same time periods. METHODS ELBW infants born in Victoria in 1991-2 were compared with regional cohorts of ELBW infants born in 1979-80 and 1985-7, and with contemporaneous normal birthweight (> 2499 g) controls, and those of birthweight 500-749 g with those of birthweight 750-999 g. RESULTS In 1979-80, 25.4% (89/351) ELBW live births survived to 2 years of age, increasing significantly to 37.9% (212/560) in 1985-7, and to 56.2% (241/429) in 1991-2. The rates of severe disability in survivors assessed were 12.4%, 6.6%, and 6.8% in the 1979-80, 1985-7, and 1991-2 ELBW cohorts, respectively. The rate of disability, overall, was significantly lower in the 1985-7 and 1991-2 ELBW cohorts compared with the 1979-80 ELBW cohort, but was significantly higher in 1991-2 ELBW infants than normal birthweight controls. Surviving children with birthweights < 750 g had significantly higher rates of sensorineural disability compared with those of birthweight 750-999 g in 1979-80, but not in 1985-7 or 1991-2. CONCLUSIONS Survival rates for ELBW babies in Victoria have progressively improved since the late 1970s. Sensorineural outcome for survivors born in 1985-7 has also improved compared with those born in 1979-80. However, there is no evidence that further reductions in adverse sensorineural outcomes into the 1990s, and these, as well as disabilities remain higher in ELBW than in normal birthweight babies.