Patrick J, Carmichael L, Chess L, Staples C
Am J Obstet Gynecol. 1984 Jan 1;148(1):35-41. doi: 10.1016/s0002-9378(84)80028-9.
In order to document the normal structure and pattern of fetal heart rate accelerations near term, we measured fetal heart rate and fetal movements for 24-hour observation intervals in 12 healthy pregnant women at 38 to 40 weeks' gestation. There were 34 accelerations per hour on the average with a mean amplitude of 22.8 bpm and a mean duration of 40.7 seconds. The longest time between successive accelerations was 37 minutes. There was a significant negative correlation between the mean daily maximum amplitude of accelerations and the mean daily fetal heart rate (r = -0.84). Fetal heart rate acceleration patterns suggested a prolonged period of fetal wakefulness during the late evening.
