Background and objectives: Deviations in birth weight from an optimum, thought to be just above average for gestational age, are known to increase both the risk of developing cerebral palsy and the risk of developing cerebral palsy of a more severe form. Influences on survival of such deviations from average birth weight for gestational age are not known.
Methods: Using a well-established, well-defined and large UK cohort of children and adults with cerebral palsy, followed from birth for nearly 25 years, we investigate the influence of deviations from average birth weight for gestational age, on survival duration, after allowing for severity of impairments.
Results: A total of 3946 cases, born between 1980 and 1996 were included. For those born much lighter than average for gestational age, more than 30% (n = 313) had a severe motor or cognitive impairment, rising to as much as 40% (n = 239) for extremely low weights. For female infants, the proportions severely impaired increased to as much as 35% (n = 49) among those born much heavier than average; no such increase was observed for heavier than average male infants. For those with four severe impairments and a birth weight close to average for gestational age, around 60% (n = 140) survived to age 15 years, compared with less than 40% (n = 9) of those born much heavier than average for gestational age. A 2-year-old child with four severe impairments and born heavy for gestational age has a predicted median life expectancy of 79% (95% CI 70% to 88%) of the average.
Conclusions: Infants with a birth weight lighter than average for gestational age have an increased likelihood of developing a more severe form of cerebral palsy. Surprisingly, among the infants who are very severely impaired, those born much lighter than average for gestational age have the longest life expectancy, and those born much heavier than average for gestational age have the shortest life expectancy.
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Funding: KH was employed as a research assistant to J Hutton and P Pharoah under an Medical Research Grant (number G9900630) “Life expectancy in children and young adults with cerebral palsy: a UK collaboration” for the duration of this work. JK was partially funded by a National Public Health Career Scientist Award from the NCCRCD (PHCS022). The Merseyside and Cheshire register is currently funded by the NHS, North of England. Collaborative Cerebral Palsy Survey receives grants from the Directors of Public Health of the Northern and Yorkshire Region and Primary Health Care Trusts. 4Child—Four Counties Database of Cerebral Palsy, Vision Loss and Hearing Loss in Children is currently funded by the Department of Health Policy Research programme under the Research Active Disease Registers Initiative. The national perinatal epidemiology unit is funded by a grant from the Department of Health, England. The Scottish Register of Children with Motor Deficit of Central Origin was originally set up in Glasgow University and funded by a grant from the Chief Scientist of the Scottish Office. The register was subsequently transferred to the care of the Information Services Division of NHS National Services Scotland. The Northern Ireland Cerebral Palsy register is funded by the Department of Health, Social Services and Public Safety.
Competing interests: JLH has served as an expert witness on life expectancy in cerebral palsy legal cases.
The various funding sources were not involved in the design or conduct of any stages of this work, or in the decision to submit for publication. The views expressed in this paper are those of the authors and not necessarily those of the Department of Health.