Parshat נח has references to the Torah prohibition against abortion. When the Noachide laws are given, included in murder is שופך דם אדם באדם, spilling the blood of man within man.
This strange wording implies terminating the life of one who is inside another human. This is interpreted as terminating the life of a fetus. This prohibition applies both to Jews and non Jews.
Rabbeinu Bechaye goes even further by saying that the ultimate corruption of the דור המבול is that they regularly killed their fetuses at forty days when it became a real viable entity. They were punished measure for measure with forty days of rain that put an end to their lives.
It is amazing that other Rabbis like the Rambam understood so much about the development of a fetus, and how the Torah made it so clear that abortion is absolutely forbidden.