NEONATAL SOCIETY ABSTRACTS
Infants born less than the 0.4th percentile for weight despite higher gestational age are at high risk of poor neurodevelopmental and growth outcome compared to very preterm infants
Presented at the Neonatal Society 2010 Summer Meeting (programme).
Venkatesh V, Chaudhary R, D’Amore A, Curley A
Neonatal Intensive Care Unit, Cambridge University Hospitals NHS Trust, Cambridge, CB2 2QQ, UK
Introduction: Many studies have reported on the long term outcomes of babies born extremely preterm. There has been less focus on babies born small for gestational age, in particular babies with a birthweight less than the 0.4th percentile.
Aim: To assess neurodevelopmental outcome and longitudinal growth parameter data in a large cohort of very low birth weight infants stratified by birthweight greater or less than the 0.4th percentile.
Methods: Data were collected from all 8 neonatal units in the Norfolk Suffolk and Cambridge Perinatal Network as part of the VLBW East Anglian Project from 1993-2002. This was a population based regional cohort of babies <1500g birthweight. Formal ethical approval was not required for the study as the local research ethics committee deemed the project to be an audit. Infants were plotted using Child Growth Foundation charts 1996 (1) to determine those born with a birthweight less than the 0.4th centile. Neurodevelopmental outcomes were assessed at 2 years and recorded on a validated standardised form based on the Health Status Questionnaire1by named local paediatricians experienced in developmental follow up. Children were assessed as having no mild, moderate and severe disability by using the Functional disability classification (2).
Results: From a cohort of 2367 babies 157 babies had birthweights less than the 0.4th percentile. 23 /157 (15%) died before 2 years of age. 128 (96%) of survivors were assessed at two years. At 2 years 47% had some disability: 26% mild, 9% moderate and 12% severe compared to infants with a birthweight greater than the >0.4th percentile whose rates of disability were mild 20%, moderate 11% and severe 8.4%. Disability rates were not significantly different although their median gestational ages differed considerably (29 vs 34 weeks p <0.05). Visual difficulties were reported in 7% of children less than the 0.4th percentile compared to 3.7% in those greater than the 0.4th percentile. 78% of babies had head circumference measurements below the 9th percentile at birth and 67% at two years of age. 63% of children less than the 0.4th percentile at birth remained less than the 9th percentile for weight and 47% were less than the 9th percentile for height at 2 years corrected age.
Table 1: Growth parameters for infants less than the 0.4th percentile
Conclusion: Despite higher median gestational age in this study infants born less than the 0.4th percentile have similar rates of moderate to severe disability as extremely preterm infants. They have higher risks of visual and hearing difficulties for their gestational age. Catch up growth, in particular head circumference, was poor overall and often asymmetric. This study demonstrates that infants born less than the 0.4th percentile for weight are at high risk of poor neurodevelopmental and growth outcome and should be allocated similar resources to those born extremely preterm.
1. Johnson A. Disability and perinatal care: measurement of health status at two years. A report of two working groups convened by the National Perinatal Epidemiology Unit and Oxford Regional Health Authority. 1994
2. World Health Organization. (2001). International Classification of Functioning, Disability and Health (ICF). Geneva: Author