Abnormal fetal heart rate patterns and percentage of creatine phosphokinase-2.

Eighteen term newborn infants who had been evaluated by internal fetal heart rate (FHR) monitoring were studied to correlate fetal monitor tracings with Apgar scores and serum creatine phosphokinase-1 (CPK2) the myocardium-specific isoenzyme of CPK. The percentage of CPK2 at 30 +/- 6 hours did not correlate significantly with Apgar scores. However, values for the percentage of CPK2 at 30 +/- 6 hours were significantly higher in neonates with abnormal FHR tracings than in those with normal FHR tracings (p less than 0.01). These preliminary data suggest that subtle intrapartum asphyxial injury may be present without adversely affecting Apgar scores.