Which statement best defines a reactive NST?

• A. Two accelerations within 20 minutes, with peak at least 15 bpm above baseline and lasting 15 seconds
• B. No accelerations within 40 minutes
• C. Continuous baseline variability with decelerations
• D. One acceleration lasting at least 60 seconds

Answer: (D)

A reactive NST is shown when the fetal heart rate reliably accelerates in response to movement, indicating good oxygenation and autonomic function. The key requirement is at least two accelerations within a 20-minute window, with each acceleration peaking at least about 15 beats per minute above baseline and lasting at least 15 seconds. This pattern demonstrates the fetus can appropriately respond to stimuli. In contrast, no accelerations in a prolonged period points to a nonreactive tracing, and continuous baseline variability with decelerations is not reactive. A single prolonged acceleration (lasting 60 seconds) does not meet the criterion for reactivity on its own. So the correct description is the one that includes two qualifying accelerations within the 20-minute interval.