These sleazebags are trying to associate abortion with slavery.
Their position is that a woman with less than full and complete autonomy over her own body is nothing more than livestock, so that’s where the slavery connection comes in.
The majority ruling of "Roe vs Wade" codified an unborn baby to be the sole property of the mother via the following clause from the 14th amendement, "nor shall any State deprive any person of life, liberty, or property, without due process of law.".