Perinatal complications and socio-economic differences in cerebral palsy in Sweden - a national cohort study.
BACKGROUND
There is a controversy regarding the existence of a socio-economic gradient for cerebral palsy. Perinatal emergencies and preterm birth increase the risk for the offspring to develop cerebral palsy. The aim of this study was to investigate the association of socio-economic indicators with cerebral palsy (CP) and the role of perinatal health as mediator of this association.


METHODS
Register study of a national cohort of 805,543 children born 1987-93, including 1,437 children with cerebral palsy that were identified in hospital discharge data from national registers. Socio-economic indicators of the household were taken from the Census of 1985. Logistic regression and chi-square analyses of linearity were used to test hypotheses.


RESULTS
There was a linear association between the incidence of CP (excluding cases caused by registered injuries or malformations) as well as of major perinatal indicators and the socio-economic status (SES) of the household of the mother (p < 0.001). Children in households with low SES had a higher odds ratio of CP (OR 1.49 [95% C.I. 1.16-1.91]) compared with high SES after adjustment for demographic confounders. This OR decreased to 1.36 (1.05-1.71) after adjustment for perinatal indicators with preterm birth as the most important mediating variable.


CONCLUSIONS
This study suggests that there is a continuous socio-economic gradient for CP in Sweden. Further studies in more complete populations of children with cerebral palsy are needed to confirm this. Perinatal complications seem to mediate some of this gradient.
Hjern
Anders
A
Centre for Epidemiology, National Board of Health and Welfare, Stockholm, Sweden. anders.hjern@socialstyrelsen.se
Thorngren-Jerneck
Kristina
K
D002547:Cerebral Palsy / Q000453:epidemiology*; D016009:Chi-Square Distribution; D015331:Cohort Studies; D005260:Female; D005865:Gestational Age; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D016014:Linear Models; D016015:Logistic Models; D008297:Male; D007744:Obstetric Labor Complications / Q000453:epidemiology*; D016017:Odds Ratio; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology*; D047928:Premature Birth / Q000453:epidemiology*; D012307:Risk Factors; D012959:Socioeconomic Factors; D013548:Sweden / Q000453:epidemiology