A fetal animal is also called a fetus, and something humans have in common with all other animals is our beginning in a fetal form, before our birth. Fetal development describes the way a fetus grows and changes over time, and when someone's in a fetal position, they're curled forward with bent arms and legs — like a fetus in its mother's womb. Fetal stems from the Latin fetus, "the bearing of young," or "a bringing forth."