CCRN Neonatal Practice Test

Fetal tone is the aspect of the Biophysical Profile that specifically evaluates muscle tone. It’s observed as spontaneous limb extension and rapid return to flexion (or sudden opening and closing of the hands), demonstrating the fetus’s neuromuscular tone. This reflects intact central nervous system control and adequate oxygenation. The other parameters assess different functions: amniotic fluid volume relates to fetal urine output and placental function; the NST evaluates fetal heart rate accelerations in response to movement; fetal breathing looks at chest wall and diaphragmatic movements; gross body movements assess activity in general but not the specific presence of tone. Because tone directly measures how well the fetus maintains muscle tone, it’s the best indicator for this parameter in the BPP.