What is the requirement for a non-stress test to be considered reactive?

A non-stress test (NST) is a common assessment used in obstetrics to monitor fetal well-being by observing the fetal heart rate in response to movements. For the test to be considered reactive, it must show evidence of fetal heart rate accelerations that signify a healthy response to the fetus's own movements.

The correct answer indicates that the criteria for a reactive NST is the presence of two fetal heart rate accelerations of at least 15 beats per minute (bpm) that occur within a 20-minute period. This pattern suggests good placental function and adequate oxygenation of the fetus, which are crucial indicators of fetal health. Each acceleration reflects the normal autonomic function and development of the fetal nervous system, providing reassurance that the fetus is not experiencing any distress.

In contrast, the other choices do not meet the established criteria for a reactive NST. For example, a single acceleration of 25 bpm does not satisfy the requirement as two accelerations are needed for a definitive conclusion. Similarly, a maternal heart rate acceleration or a constant fetal heart rate does not provide the necessary information about fetal well-being and does not reflect the expected responses needed for a reactive test.