Association of cerebral palsy with Apgar score in low and normal birthweight infants: population based cohort study
BMJ 2010; 341 doi: https://doi.org/10.1136/bmj.c4990 (Published 07 October 2010) Cite this as: BMJ 2010;341:c4990
- Kari Kveim Lie, senior researcher1,
- Else-Karin Grøholt, senior researcher1,
- Anne Eskild, professor23
- 1Division of Epidemiology, Norwegian Institute of Public Health, Oslo, Norway
- 2Department of Obstetrics and Gynaecology and Medical Faculty Division, Akershus University Hospital, Nordbyhagen, Norway
- 3Division of Mental Health, Norwegian Institute of Public Health, Oslo, Norway
- Correspondence to: K Kveim Lie, Division of Epidemiology, Norwegian Institute of Public Health, PO Box 4404, Nydalen, 0403 Oslo, Norway kari.kveim.lie{at}fhi.no
- Accepted 23 July 2010
Abstract
Objectives To assess the association of Apgar score 5 minutes after birth with cerebral palsy in both normal weight and low birthweight children, and also the association with the cerebral palsy subdiagnoses of quadriplegia, diplegia, and hemiplegia.
Design Population based cohort study.
Setting The Medical Birth Registry of Norway was used to identify all babies born between 1986 and 1995. These data were linked to the Norwegian Registry of Cerebral Palsy in Children born 1986-95, which was established on the basis of discharge diagnoses at all paediatric departments in Norway.
Population All singletons without malformations born in Norway during 1986-95 and who survived the first year of life (n=543 064).
Main outcome measure Cerebral palsy diagnosed before the age of 5 years.
Results 988 children (1.8 in 1000) were diagnosed with cerebral palsy before the age of 5 years. In total, 11% (39/369) of the children with Apgar score of less than 3 at birth were diagnosed with cerebral palsy, compared with only 0.1% (162/179 515) of the children with Apgar score of 10 (odds ratio (OR) 53, 95% CI 35 to 80 after adjustment for birth weight). In children with a birth weight of 2500 g or more, those with an Apgar score of less than 4 were much more likely to have cerebral palsy than those who had an Apgar score of more than 8 (OR 125, 95% confidence interval 91 to 170). The corresponding OR in children weighing less than 1500 g was 5 (95% CI 2 to 9). Among children with Apgar score of less than 4, 10-17% in all birthweight groups developed cerebral palsy. Low Apgar score was strongly associated with each of the three subgroups of spastic cerebral palsy, although the association was strongest for quadriplegia (adjusted OR 137 for Apgar score <4 v Apgar score >8, 95% CI 77 to 244).
Conclusions Low Apgar score was strongly associated with cerebral palsy. This association was high in children with normal birth weight and modest in children with low birth weight. The strength of the association differed between subgroups of spastic cerebral palsy. Given that Apgar score is a measure of vitality shortly after birth, our findings suggest that the causes of cerebral palsy are closely linked to factors that reduce infant vitality.
Footnotes
We thank the chief medical officers at the paediatric departments in Norway for providing diagnostic information on children with cerebral palsy.
Contributors: KKL and AE planned the study. KKL established the Norwegian Registry of Cerebral Palsy in children born 1986-95. KKL and E-KG performed the analysis, and KKL and AE wrote the majority of the paper. KKL, AE, and E-KG discussed the design, edited the paper, and agreed on the final version. KKL is guarantor. All authors had full access to all of the data (including statistical reports and tables) in the study and can take responsibility for the integrity of the data and the accuracy of the data analysis.
Funding: The study was funded by the Norwegian Foundation for Health and Rehabilitation, which had no role in the study planning, data collection, or analysis, or in the writing the article or in the decision to submit the article for publication.
Competing interests: All authors have completed the Unified Competing Interest form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: no support from any organisation for the submitted work; no financial relationships with any companies that might have an interest in the submitted work in the previous 3 years; no other relationships or activities that could appear to have influenced the submitted work.
Ethical approval: The study was approved by the Norwegian Board of Health, the Norwegian Data Inspectorate, and the Regional Committee for Medical Research Ethics.
Data sharing: No additional data available.
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