Black's Medical Dictionary is a standard reference source used by medical professionals throughout the English-speaking world.  Their 1987 edition begins its entry on "foetus" as follows:

  

“FOETUS is the name given to the child while still within the womb. The human being, like the young of all animals, begins as a single cell ... “
  

"The property of 'life' is present from the very beginning, although the movements of the foetus are not felt by the mother till the fifth month."

 

An American Holocaust