Even if I thought an embryo... was a person and in possession of rights (for the record, I don't), no person has a right to use the body of another without consent. You can't be forced to donate a kidney to a dying relative. The state can't require you to donate blood, plasma or bone marrow (despite the procedures being far safer and less invasive than pregnancy.) Hell, your corpse can't be harvested of lifesaving materials without prior consent.
- Pro-choice. Don't force your religion on me.
The pro-life movement literally believes pregnant women should have fewer rights than corpses.