Fetal reacting bradycardia.

Acute and abrupt fetal bradycardia are considered to be vagal in origin. In addition to head compression and funis compression bradycardias, we will report on those acute fetal bradycardias occurring during maternal seizures and maternal voiding, during aortocaval compression, during terminal labor, and during the immediate postpartum period. While certain mechanisms are known which can explain some or parts of these bradycardias, we conclude that in the clinical setting information is insufficient to determine their etiology with precision. Instead of labeling abrupt fetal heart rate pattern as resulting from either head or funis compression, it is suggested that the patterns be described according to their severity and duration. Such acute fetal bradycardias can be detrimental in terms of reduced umbilical flow. Administration of atropine may be indicated in the otherwise healthy fetus with acute bradycardia.