The ability to diagnose severe chronic fetal distress-impending death utilizing the six different definitions of decreased fetal movement (DFM) currently in use, was evaluated retrospectively in 616 high-risk pregnant women. The study reveals the superiority of two definitions as prognostic tools: The "movements alarm signal" (MAS), i.e. no fetal movements (FM) for at least 12 hours with audible fetal heart beats, and "ten and less FM" (less than or equal to 10 FM), i.e. ten or fewer FM in 12 hours. The application of these definitions distinguished two groups of patients which included significantly more poor outcomes than were contained by the groups of patients based on the other definitions. MAS was the definition also selecting the group with fewest false-positive cases. The monitoring of FM while utilizing one of the above two definitions of DFM as cut-off points for suspected impending fetal death is a useful adjunct in high-risk pregnancy management.