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

baseline, with a duration of >15 seconds but < 2 min from onset to return.
At <32 weeks gestation, an acceleration has a peak of ≥10 beats/min above
baseline, with a duration of ≥10 sec but <2 min from onset to return.