USMLE Step 2 CK Lecture Notes 2019: Obstetrics/Gynecology (Kaplan Test Prep)

the sympathetic and parasympathetic nervous system.

Figure I-16-3. Fetal    Heart   Rate    Baseline    Variability

Acceleration: A visually apparent abrupt increase (onset to peak in <30
seconds) in the FHR. These are mediated by the sympathetic nervous system in
response to fetal movements or scalp stimulation.

Absent  amplitude   range   undetectable

Minimal amplitude   range   detectable  but ≤5  beats/min

Moderate    (normal):   amplitude   range   6–25    beats/min

Marked: amplitude   range   >25 beats/min

At  ≥32 weeks   gestation,  an  acceleration    has a   peak    of  >15 beats/min   above