And whether it's human.
There are a lot of sophists out there with arguments denying the humanity of the unborn baby. With them I prefer a negative approach, placing the burden of proof on them, where it belongs. If the "tissue" isn't part of the mother (it has different DNA), then what type of being is it? If they answer anything except for human then the next logical question is, what is it?
The 'only tissue, only a clump of cells' argument has so many flaws it is hardly an effort to refute them. From the first cell division following fertilization/conception, the individual human being builds its own capsule and its own body. Tissue from the placental sac and the yolk sac are later incorporated into the sinews and gut of the growing child. The placental sac and the fluid within are all produced by the newly conceived individual, not the woman's body, as proven by extensive embryological studies. It is the amazing God programmed ability of the newly conceived human being that protects it from tissue rejection by the woman's body, acting as a barrier and a type of camouflage that prevents the woman's immune system from attacking and shedding the 'other' life within her body attaching to her uterine tissues. The new conceptus sends out the chemical messengers to bring about the supportive actions from the woman's body. At the very outset, it is the newly conceived individual human being who directs the gestational program as it seeks to survive, existing exactly normal in form and function for its age, as it ages, and for the environment in which its life has begun.