Final answer:
Late deceleration, also known as utero insufficiency, is when the fetal heart rate slows down during contractions. This is caused by a decrease in oxygenated blood flow to the fetus. It can lead to fetal distress and may require an emergency birth.
Step-by-step explanation:
Late deceleration or utero insufficiency is a condition where the fetal heart rate slows down during contractions. This occurs because contractions reduce the oxygenated blood flow to the fetus. It is important to have a period of relaxation after each contraction to restore oxygenated blood flow to the fetus. If the contractions are too powerful or lengthy, the fetus may experience fetal distress, which can result in an emergency birth.