As an "anarcho" you should understand that no thing, any, thing, can rule over another. A child acts much like a parasite to the host. It will and can kill the mothr to survive. This is what the biology of this life dictates.
Now put aside your ethics and look at it from the mother's perspective. seeing it from the "oh no, the child is so innocent" doesn't really cut it
People can, and do, incur positive obligations all the time. As I've said elsewhere, if the child poses a risk of harm to the mother, then the mother is justified in using whatever means necessary to preserve her life. Barring this instance, though, killing another human being - which a fetus undoubtedly is - is not moral or justifiable.