[Patterns of fetal heart frequency during the second stage of labour and expulsion period--typical patterns, frequency, risk of acidosis and evaluation (author's transl)].

Four patterns of fetal heart frequency with normocardia, two with tachycardia and three with bradycardia are described during the expulsion period. The most frequent patterns are normocardia with decelerations (48%), normocardia with decelerations and final bradycardia (21.1%) and basal bradycardia with decelerations (13.5%). The frequency of acidosis (pH of the umbilical artery less than or equal to 7,200) of these three patterns amounts to 8.3, 24.1 respectively 26.7%. The mean values of pHUA of normocardia with decelerations and final bradycardia, bradycardia, bradycardia with decelerations, tachycardia with decelerations and final bradycardia with prepathologic respectively pathologic Scores (Hammacher's Score, greater than or equal to five points) range from preacidosis to acidosis. Scoring of cardiotocograms seems to be of greater clinical significance than the measurement of deceleration areas.