Mike has an interesting post over at Prosblogion. Before sending you there, consider:
1. Given the exclusive options of saving the life of a puppy or saving the life of fetus, a pregnant woman is morally permitted to save her puppy rather than the fetus.
2. If the fetus had greater moral standing than puppies, it would not be permissible for the pregnant woman to save the puppy rather than the fetus.
C2. :. Being a fetus does not itself confer greater moral standing than being a puppy.