A client at 42 weeks' gestation is 3 cm dilated and 30% effaced with membranes intact and the fetus at +2 station. fetal heart rate (fhr) is 140 to 150 beats/minute. after 2 hours, the nurse notes on the external fetal monitor that for the past 10 minutes, the fhr ranged from 160 to 190 beats/minute. the client states that her baby has been extremely active. uterine contractions are strong, occurring every 3 to 4 minutes and lasting 40 to 60 seconds. the nurse suspects fetal hypoxia based on which finding?