I didn't include "Zygote" below because most prochoicers don't even know what those are, let alone use the term.
em·bry·o
/ˈembrēˌō/
noun
an unborn or unhatched offspring in the process of development, in particular a human offspring during the period from approximately the second to the eighth week after fertilization (after which it is usually termed a fetus).
synonyms: fetus, fertilized egg, unborn child/baby
fe·tus
/ˈfēdəs/
noun
an unborn offspring of a mammal, in particular an unborn human baby more than eight weeks after conception.
synonyms: embryo, fertilized egg, unborn baby, unborn child