What is the name of the test used for fetal well-being that measures fetal heart rate reactivity?

The test used for assessing fetal well-being that specifically measures fetal heart rate reactivity is called the Non-stress test (NST). This test is designed to evaluate how the fetal heart rate responds to movements of the fetus. During an NST, a fetal heart rate monitor is applied to the mother's abdomen, and it records the heart rate pattern and variations over a certain period.

A reactive NST indicates that the fetal heart rate accelerates appropriately with fetal movements, suggesting adequate oxygenation and a healthy nervous system. The absence of reactivity could prompt further investigation, as it may suggest potential fetal distress or other issues.

Other tests, such as amniocentesis, primarily involve sampling amniotic fluid for genetic or biochemical analysis rather than directly assessing heart rate. The Biophysical profile (BPP) combines NST with other assessments like fetal movements, tone, breathing, and amniotic fluid level to create a broader picture of fetal well-being. The Contraction stress test (CST) monitors the fetal heart rate in response to uterine contractions, which is more indicative of the fetus's ability to handle the stress of labor rather than just reactivity to movement.