Of 403 newborns with either fetal heart rate (FHR) bradycardia or tachycardia during the last ten minutes of the second stage of labor, 20% had an umbilical cord pH of less than 7.20 at birth compared with only 4% of newborns who had a normal FHR during the last ten minutes of labor (P<.0001). Thirty (18%) of 165 neonates with mild bradycardia and 33 (27%) of 121 neonates with moderate to marked bradycardia had cord pH values of less than 7.20 at birth (P<.0001). Of the 117 neonates with tachycardia during the last ten minutes of the second stage, 17 (15%) had a pH of less than 7.20 (P<.0001). There was a significant increase in low cord pH values when FHR variability was absent when compared with normal variability (P<.0001). © 1984 by The American College of Obstetricians and Gynecologists.
