Apgar scores and cerebrospinal fluid beta-endorphinlike immunoreactivity during the first day of life. Preliminary observations.

beta-Endorphinlike Immunoreactivity (BLI) was measured in sterile, bloodless samples of cerebrospinal fluid (CSF) during the first 24 hours of life in order to assess the relationship between perinatal asphyxia and endogenous opioid activity within the central nervous system. The median CSF BLI in infants with one-minute Apgar scores of 1 to 4 was 148 pg/mL (range, 96 to 171 pg/mL) and that of infants with Apgar scores of 5 to 9 was 78 pg/mL (range, 25 to 162 pg/mL). The linear regression equation correlating CSF BLI with one-minute Apgar score was y = -10.7x + 169.1. Our findings of a highly significant inverse correlation between one-minute Apgar scores and CSF BLI support the hypothesis that perinatal asphyxia is associated with increased activity of opioid systems in the central nervous system.