In a laboring patient with external fetal monitoring, which tracing finding is most consistent with decreased fetal oxygenation due to uteroplacental insufficiency?

• A. Accelerations
• B. Prolonged deceleration
• C. Late decelerations
• D. Small accelerations only

Answer: (C)

In labor, patterns of fetal heart rate reflect how well the fetus is being oxygenated. When placental perfusion is reduced (uteroplacental insufficiency), contractions cut off placental blood flow and oxygen delivery. The tracing classically shows late decelerations: a gradual fall in fetal heart rate that begins after the start of a contraction, reaches a nadir after the contraction peaks, and returns to baseline after the contraction ends. This timing indicates the fetus becomes transiently hypoxic during contractions and takes longer to recover, pointing to compromised placental function. Accelerations are reassuring and indicate good oxygenation, while prolonged decelerations signal more severe or sustained hypoxia but are not as specifically linked to placental insufficiency as late decelerations.