Final answer:
Fetal distress can occur when contractions are too powerful or lengthy for oxygenated blood to be restored to the fetus. This can result in an emergency birth.
Step-by-step explanation:
Fetal distress, which is measured as a sustained decrease or increase in the fetal heart rate (FHR), can result from severe contractions that are too powerful or lengthy for oxygenated blood to be restored to the fetus. This can be an emergency situation and may require an emergency birth with vacuum, forceps, or Caesarian section.