Objective: To investigate the association of asphyxia-related conditions (reducing blood flow or blood oxygen levels in the fetus) with spastic cerebral palsy (CP) considering different gestational age groups and the timing of risk.
Design: Population-based case-control study.
Setting: Danish Cerebral Palsy Register in eastern Denmark and Danish Medical Birth Register.
Population or sample: 271 singletons with spastic CP and 217 singleton controls, frequency matched by gestational age group, born 1982-1990 in eastern Denmark.
Methods: Data were abstracted from medical records, and a priori asphyxia-related conditions and other risk factors were selected for analysis. Each factor was classified according to the time at which it was likely to first be present.
Main outcome measures: Spastic CP.
Results: Placental and cord complications accounted for the majority of asphyxia conditions. In multivariate analysis, placental infarction was significantly associated with a four-fold increased risk for spastic quadriplegia and cord around the neck was significantly associated with a three-fold increased risk for spastic CP overall. The combination of placental infarction and being small for gestational age (SGA) afforded an especially high risk for spastic quadriplegia. Placental and cord complications were present in 21% of cases and 12% of controls.
Conclusions: The risk for spastic quadriplegia from placental infarction may be linked in some cases with abnormal fetal growth (17% of all children with spastic quadriplegia and 3% of control children both had an infarction and were SGA) -- suggesting an aetiologic pathway that encompasses both factors. The risk for spastic CP from cord around the neck is not accounted for by other prepartum or intrapartum factors we examined. Considering the relative timing of risk factors provides a useful framework for studies of CP aetiology.