Improved outcome to two years of very low-birthweight infants: fact or artifact?

In 1966-70, the survival rate for very low-birthweight (VLBW) children born in a tertiary perinatal centre was 37.1 per cent but by 1980-82 it had increased to 68.3 per cent. The latter cohort had a significantly reduced prevalence of strabismus, myopia and a head circumference under the 10th percentile, but a significantly increased prevalence of cerebral palsy compared with the 1966-70 VLBW children. Survivors born in 1980-82 had a significantly increased mean Mental Development Index (MDI) on the Bayley Scales compared with the sub-group of survivors born in 1968-70 but there was also a significant improvement in mean MDI over time for a group of normal-birthweight children. No improvement of MDI scores of VLBW survivors in the 1980-82 cohort could be attributed solely to perinatal care. The two-year-old VLBW children in the 1980-82 cohort had similar rates of sensorineural impairments, disabilities and mean MDI to those who would have survived with the care available in 1966-70. It is concluded that survival of VLBW infants has improved in recent times but that neurodevelopmental outcome still lags behind that of normal-birthweight peers.