THE EFFECTS OF PERINATAL HYPOXIC RISK ON DEVELOPMENTAL OUTCOME IN EARLY AND MIDDLE CHILDHOOD - A TWIN STUDY

The goal of this study of 66 twins was to determine whether motor and cognitive functions assessed in early and middle childhood are vulnera ble to perinatal hypoxic risk. In an earlier study of 76 infant and to ddler twins (S. Raz, F. Shah, & C. Sander, 1996), the authors found th at intrapair discrepancy on the Mental Developmental Index, but not on the Psychomotor Developmental Index, of the Bayley Scales of Infant D evelopment was associated with discordance for perinatal hypoxic risk. The twins at lower risk outperformed their higher risk co-twins. In t he present study the authors sought to establish in a new sample of pr eschool and school-age twins whether gaps in performance persist into early and middle childhood. Although the disparity in hypoxic risk bet ween the co-twins was typically moderate, significant intrapair differ ences were observed on the measure of motor performance. Among the mot or abilities examined, skills involving visually guided ballistic arm movements appeared to be the most vulnerable to perinatal risk.