What defines a reactive NST?

What defines a reactive NST?

• A. 2 accelerations of 15 bpm for 15 seconds within 20 minutes
• B. No accelerations within 40 minutes
• C. One acceleration of 20 bpm for 10 seconds
• D. Continuous baseline variability

Answer: (A)

A reactive NST shows that the fetus is responding to movement with repeated brief increases in heart rate above the baseline during the monitoring period. These accelerations indicate intact oxygen delivery and a functioning autonomic nervous system, which is reassuring. The key idea is that there are multiple accelerations that occur in response to fetal activity within the observation window, not just one or none. If there are no accelerations, or only a single brief acceleration, the tracing is considered nonreactive and suggests the need for further assessment. Baseline variability by itself is a normal feature to note, but it doesn’t define reactivity on its own. If the tracing is nonreactive, clinicians may use additional testing or stimulation to further evaluate fetal well-being.