Table 2.

Classification of the decelerations in relation to uterine contractions.

Early	Deceleration onset synchronized with uterine-contraction onset; shallow short-lasting deceleration with normal variability within the deceleration
Late	Deceleration onset during the second half of uterine contraction; gradual onset and/or gradual return to the baseline and/or reduced variability within the deceleration
Variable	Deceleration uncorrelated to any uterine contraction; a rapid drop and good variability within the deceleration; variable in size and shape
Prolonged	Deceleration lasting more than 3 minutes