Final answer:
The first sign of fetal death in late pregnancy is the absence of fetal heart tones.
Step-by-step explanation:
In late pregnancy, the first sign of fetal death is usually the absence of fetal heart tones. This means that when the healthcare provider listens to the baby's heartbeat using a device called a Doppler, they are not able to detect any heartbeat. This can indicate that the baby has passed away in the womb.