Background Severe intrauterine growth restriction places infants at risk of adverse neurodevelopmental outcomes. As survival rates of low birth weight infants have increased have the number of intact survivors increased proportionately or is there a higher morbidity rate in those infants below the 0.4th centile?

Methods Prospective geographically based cohort study of very low birthweight infants (<1500 g) from 8 UK neonatal units from 1993 to 2002. Infants with a birth weight below 0.4th centile were identified using UK standard growth charts. Infants were assessed at 2 years using prestructured forms based on the Health Status Questionnaire. Data were analysed for disability rates amongst surviving infants.

Results 91.5% (2367/2586) VLBW infants survived to admission to the neonatal unit. Of these 6% (153/2367) had a birth weight <0.4th centile; 128 infants <0.4th centile survived and were assessed at two years corrected age. Overall disability rates were similar (<0.4th centile; mild disability: 19.5%, mod-severe; 22.7%) versus >0.4th centile (mild; 20.9%, mod-severe; 19.2%). There was a trend towards decreased rates of cerebral palsy (3.1% (4/128) in the <0.4th centile group versus 5.4% in infants >0.4th centile).

Conclusion In this study overall disability rates were similar although infants <0.4th centile had lower rates of cerebral palsy. This may reflect differences in gestational age between the two groups. Larger numbers are required to analyse subgroups within this population by gestational age.