NCC Certified Electronic Fetal Monitoring (C-EFM) Practice Exam

A reactive non-stress test (NST) is characterized by the presence of two or more accelerations of the fetal heart rate within a 20-minute monitoring period. This is an important indicator of fetal well-being, as accelerations typically reflect healthy autonomic nervous system responses and fetal activity. The presence of these accelerations suggests that the fetus is receiving adequate oxygen and is not experiencing distress.

In the context of fetal monitoring, accelerations are defined as an increase in the fetal heart rate by at least 15 beats per minute lasting for at least 15 seconds, which reflects a positive response to stimuli, such as fetal movement. This serves as an assurance that the fetus is thriving during the assessment period.

The other choices do not capture the specific criteria for a reactive NST. For instance, decelerations are noted as potential signs of fetal distress rather than indicators of a reactive result. Changes in maternal posture can influence fetal heart rate patterns but aren't part of the NST definition. A flat baseline fetal heart rate, lacking variability, can be indicative of potential issues rather than a sign of fetal health. Thus, the definition of a reactive NST is primarily centered on the observation of accelerations in the fetal heart rate, which validates the correct answer.