Electronic fetal monitoring shows early decelerations. What is the most likely cause?

• A. Head compression
• B. Cord compression
• C. Placental insufficiency
• D. Uterine contractions

Answer: (A)

Early decelerations occur when the fetal head is compressed as contractions push the baby down the birth canal. This compression stimulates the fetal vagus nerve, briefly slowing the heart rate. The key sign is that the deepest point of the deceleration happens at the same time as the contraction peak. This pattern is usually reassuring and reflects normal descent of the head through the pelvis, so no intervention is needed if there are no other signs of distress. Cord compression causes abrupt, variable decelerations that don’t line up with the contraction peak; placental insufficiency causes late decelerations that begin after the contraction peak and recover after the contraction ends. Contractions themselves are part of labor, but the specific cause of early decelerations is head compression during those contractions.