It is, however, mentioned in the Mishnah. A fetus is not a person under Rabbinical law, but the Noahide prohibition on spilling blood still applies to a fetus, so abortion is generally wrong, but does not rise to the level of murder. Therefore, the Mishnah allows for abortion if there is a complication that puts the life of the mother in danger.
IU_Curmudgeon was banking on the fact that the Bible does speak of miscarriages, and a miscarriage is medically defined as a "spontaneous abortion." Obviously, Exodus isn't talking about abortion the way you meant it (or anyone else in this thread), but he's trying to use semantics to call me stupid, because he still hasn't figured out that you and I are not the same person.