Which test is used to assess fetal well-being by measuring fetal heart rate accelerations in response to fetal movement?

• A. Non-stress test (NST)
• B. Contraction stress test
• C. Vascular Doppler study
• D. Biophysical profile

Answer: (A)

Fetal well-being is assessed by whether the heart rate increases in response to fetal movement. This pattern, called a reactive response, indicates a healthy autonomic nervous system and adequate oxygenation through the placenta. In this test, external sensors monitor the fetal heart rate and movement over about 20 minutes. A reactive result means there are at least two accelerations—instances where the heart rate rises above baseline by about 15 beats per minute (15 bpm) for at least 15 seconds (some guidelines use 10 bpm for at least 10 seconds when the fetus is younger than 32 weeks)—occurring with movement. The presence of these accelerations together with normal baseline variability suggests the fetus is likely well-oxygenated and not under acute distress.

If accelerations are absent or insufficient, it signals potential placental insufficiency or fetal hypoxia, prompting further evaluation or different testing. The other tests look at different aspects: contraction-induced stress tests evaluate how the fetal heart rate responds to contractions, not to movement; vascular Doppler studies assess blood flow in the umbilical and fetal vessels rather than heart-rate responses to movement; and a biophysical profile combines several items, including the NST, but the measure described—acceleration in response to fetal movement—is the hallmark of a non-stress test.