Which decelerations on a fetal monitor are most concerning for fetal hypoxia?

• A. Late or variable decelerations
• B. Early decelerations
• C. Accelerations
• D. No decelerations

Answer: (A)

Late decelerations signal placental insufficiency and a lack of adequate oxygen reaching the fetus during contractions. They start after the contraction peaks and gradually return to baseline, which shows the fetus isn’t tolerating the stress of the contraction well. Variable decelerations are abrupt drops in heart rate that can result from cord compression; when they’re repetitive or deep, they can indicate possible hypoxia. In contrast, early decelerations are usually from head compression and are generally benign, and accelerations reflect good oxygenation and fetal activity. No decelerations alone aren’t enough to rule out distress if other signs are present. So patterns most concerning for hypoxia are late decelerations, and variable decelerations can also be alarming depending on their pattern. If these appear, clinicians typically implement intrauterine resuscitation measures and monitor closely.