Classified as normal/atypical/abnormal: "Normal" - baseline heart rate between 110-160 with moderate variability (5-25 interbeat variability) and 2 qualifying accelerations in 20 minutes with no decelerations.
Previous terminology: Reactive/non-reactive: *Reactive (normal) - presence of two or more fetal heart rate accelerations within a 20-minute period, with or without fetal movement discernible by the woman. Accelerations are defined as 15 bpm above baselines for at least 15 seconds if beyond 32 weeks gestation, or 10 bpm for at least 10 seconds if at or below 32 weeks.
Nonreactive - presence of less than two fetal heart rate accelerations within a 20-minute period over a 40-minute testing period.
^Smith, C. V.; Nguyen, H. N.; Phelan, J. P.; Paul, R. H. (1986). "Intrapartum assessment of fetal well-being: a comparison of fetal acoustic stimulation with acid-base determinations". Am J Obstet Gynecol155: 726–728. doi:10.1016/s0002-9378(86)80007-2.
^Chervenak, Frank A.; Kurjak, Asim (2006). Textbook of Perinatal Medicine, Second Edition (Two Volumes). Informa Healthcare. ISBN1-84214-333-6.