Modanlou and Freeman listed criteria to define the “true” sinusoidal heart rate (SHR) pattern on the fetal cardiotocogram.



(1) fetal heart rate in beats per minute (vertical axis)

(2) time (horizontal axis)


Features of ture SHR:

(1) baseline fetal heart rate stable and from 120 to 160 beats per minute

(2) range for fetal heart rate amplitude usually between 5 to 15 beats per minute

(3) 2 to 5 cycles per minute in a sinusoidal pattern

(4) oscillation of sinusoidal wave above and below the baseline

(5) minimal short-term variability (relatively uniform pattern)

(6) absence of normal fetal heart rate variability or reactivity


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