Late decelerations start at or after the peak of a contraction and are considered to be a sign of uteroplacental insufficiency.
The depth of late decelerations is probably not as significant as their presence. If frequent, they can be a sign of fetal distress and an indication for prompt delivery.
If late decelerations are accompanied by loss of beat-to-beat variability, it is generally considered an indication for urgent or emergent delivery, either by cesarean section or operative delivery (forceps or vacuum extraction), depending upon the state of the labor.
The vast majority of fetuses with nonreassuring fetal heart tracings are completely normal.