Table 2. Proposed Physiological Categorization of FHR Decelerations [6, 26].

Early decelerations	Recurrent# slowing of FHR with onset early in the contraction and return to baseline at the end of contraction.
Late decelerations	Recurrent slowing of FHR with onset mid to end of contraction and nadir more than 20 s* after peak of contraction and ending after the contraction. If baseline variability is less than 5 beats/min, then the definition would include decelerations less than 15 beats/min.
Variable decelerations	Recurrent slowing of FHR with varying time relationship to the contraction cycle. They tend to markedly vary in shape.

The confusing term “uniform” is avoided. ^#“Recurrent” - associated with more than 50% contractions [11]. *The 20 s lag-time is based on expert consensus [24] and seems practically useful.