In Reply.—Dr Copian is correct that a higher proportion of infants in the Collaborative Perinatal Project of the National Institute of Neurological and Communicative Disorders and Stroke (NCPP) study population who had birth complications and low Apgar scores died early and therefore were not candidates for the development of cerebral palsy. That information was presented in an earlier report in JAMA.1 Since our recent report was concerned chiefly with whether a surviving term child with birth complications was at heightened risk for disability if he or she was asymptomatic as a newborn, we did not reexamine the question of mortality.
It would be possible to speculate, for children in this study who died, the effect on the results if they had lived. If the children who died had lived and had had a similar distribution of neonatal signs as the children who really did survive, then the comparative risks of cerebral palsy in the complicated and uncomplicated groups would have remained substantially unchanged. If, on the other hand, a large proportion of the nonsurviving children had lived and had a very high rate of multiple neonatal signs, then the results might have been markedly different. There seems to be no reasonable argument based on NCPP data for a choice of one assumption