1) The fetus is a part of the mother’s body. if the fetus is a part of the mother’s body, then all pregnant women are chromosomal mosaics. That is, they are organisms that have two sets of genomes. Chromosome mosaicism is a rare disorder and is not synonymous with pregnancy. There is no such thing as “transient chromosomal mosaicism.” Furthermore, if the fetus is a part of the mother’s body, then half of pregnant women are hermaphrodites — i.e., they contain both male and female tissues. Needless to say, “transient gestational hermaphroditism” is not a recognized medical disorder.
Furthermore, if a new human life begins by a piece of the mother’s body becoming a new organism, then human beings reproduce by budding. Budding is a form of asexual reproduction used by some species of worms, sponges, corals, and microorganisms, but it is not a means of human reproduction.
There is no biological sense to be made of the claim that “the fetus is part of the mother’s body.” The claim leads to scientific implications that are nonsense.Michael Egnor, “If a Fetus Isn’t a Human Being, What Is It?” at Evolution News (May 11, 2022)
It appears that some people will say — and literally believe — anything to get rid of a kid. But it will come back to haunt them if they also say they believe in science.
You may also wish to read: Must we be able to reason to be thought of as human persons? Michael Egnor: A common argument as to why abortion is generally ethical is that the unborn child cannot reason. Reason is a natural quality of the human being but, like everything in nature, it develops in stages. One can’t say it doesn’t exist when undeveloped.