Antecedents of cerebral palsy. Multivariate analysis of risk.

We examined prenatal and perinatal factors predicting cerebral palsy, using multivariate analysis to investigate which factors were most important and the proportion of cases for which they accounted. Maternal mental retardation, birth weight below 2001 g, and fetal malformation were among the leading predictors. Breech presentation was also a predictor, but breech delivery was not. A third of the children with cerebral palsy who had breech presentations had a major noncerebral malformation. Among 189 children with cerebral palsy, 40 (21 percent) had at least one of three clinical markers suggestive of asphyxia; only 17 of these 40 children (9 percent of all cases) lacked major congenital malformation or other intrinsic defects that might have contributed to an unfavorable outcome. When all the principal risk factors present by the time labor began were considered, the 5 percent of the population at highest estimated risk was seen to have contributed 34 percent of the cases. When all the risk factors present during the period beginning before pregnancy and extending through the nursery stay were included, the 5 percent at highest risk was seen to have contributed 37 percent of the cases. Thus, the inclusion of information about the events of birth and the neonatal period accounted for a proportion of cerebral palsy only slightly higher than that accounted for when consideration was limited to characteristics identified before labor began.