The best replacement for fetus is embryo.

The best alternatives to fetus are rated as following:
★★★★★  embryo
★★★★★  baby
★★  foetus
★  infant
  female fetus
  fibroid
  parasite
  unborn child
  non active fetus
  zygote
  fetuses
  mother
  animal fetus
  human fetus
  inactive fetus

Your alternative for fetus is not listed? Suggest!
Speaking about fetus, one probably shouldn't forget about enlarged kidneys.

Other search terms related to fetus and their ratings are:
★★★★★ enlarged kidneys
★★★★ water on the brain
★★★ amniotic fluid
★★★ enlarged kidney
★★★ no heartbeat
★ placenta
★ yolk sac
★ enlarged heart
kidney problems
You have in mind a companion for fetus and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of fetus in all years. Click on graph for more.
fetus
embryo
baby