Cerebral palsy is the most common cause of severe physical disability in children in developed countries. The frequency of the disorder in children born at low birthweights increased sharply around 1980, but the cause of the condition is still poorly understood. Previous research has indicated that low birthweight in term babies is associated with increased risk of cerebral palsy.
Stephen Jarvis from the University of Newcastle, UK, and colleagues compared data from ten European registers for around 4500 children with cerebral palsy born between 1976 and 1990 with the number of births in each study population. Weight and gestational age of these children were compared with reference standards for the normal spread of gestational age and weight-for-gestational age at birth.
Babies of 32-42 weeks' gestation with a birthweight for gestational age below the 10th percentile were 4-6 times more likely to have cerebral palsy than were children in a reference band between the 25th and 75th percentiles. In children with a weight above the 97th percentile, the increased risk was smaller (up to a threefold increase) but was still statistically significant. Babies born with a slightly heavier than average birthweight were at the lowest risk of developing cerebral palsy.
The investigators comment that evidence is pointing to endocrine pathways, infection, coagulation defects, or even a "vanishing twin" episode early in pregnancy as the primary cause in many cases of cerebral palsy.
In an accompanying Commentary (p 1089), Mario C Petersen and Frederick B Palmer from the University of Tennessee, USA, conclude: "Importantly, Jarvis and colleagues distinguish the risk of cerebral palsy by use of two different kinds of growth standards: weight recorded at birth and expected birth weight based on prenatal ultrasonography measurements. Their data supports the assumption that the birthweight of premature infants is not "normal"-ie, optimal-and that using the expected weight could be a more valid measure of risk for the child during pregnancy and after birth.
Further studies will need to prove the usefulness of this approach in clinical practice. Finally, this study adds to the evidence that most cerebral palsy is of prenatal origin rather than primarily due to obstetric complications."
Contact:
Dr. Mary-Jane Platt, Senior Lecturer in Public Health, University of
Liverpool, UK; T) 44-0-151-794-5576 or
44-0-7775-746914; E)
mailto:mjplatt@liv.ac.uk
Professor Stephen N Jarvis, School of Clinical Medical Sciences (Child Health), University of Newcastle, The Royal Victoria Infirmary, Queen Victoria Road, Newcastle Upon Tyne, NE1 4LP, UK; T) 44-0-7714-235227; E) s.n.jarvis@ncl.ac.uk
Dr. Mario C Peterson, Department of Pediatrics and Boling Center for Developmental Disabilities, University of Tennessee Health Science Center, Memphis, TN 38105, USA ; T) E) mpetersen@utmem.edu.
Journal
The Lancet