This is a non-sequitur. Our inability to remove organisms from our body has absolutely no relevance with the legality or morality of abortion. Abortion is clearly possible; what difference does it make if there are other organisms present in a woman's body that cannot be removed? (I'm not being deliberately obtuse; I'm trying to see the relevance, but failing to do so.)
The point is quite clear. We are naturally unable to exercise total control over all our natural functions. A good theory to explain this is that it is an evolutionary feature, so as to ensure our survival. If we could, for example, choose to remove the natural flora in our bodies, the likely result would be increased infection and therefore increased death. Perhaps why we cannot naturally abort other human beings is for a similar natural reason. ... Just a contemplation.
You (along with several other posters in this thread) are confusing what is morally right with what is legally right. Whether abortion is morally right is an enormously complex question that is dependent on each pregnant woman's individual circumstances. But, as I understand it, the abortion debate centers on whether abortion is legally permissible. I hold that it should be legal, as the prohibition of abortion would violate a pregnant woman's right to the control of her own body. No one--not you nor I nor the fetus nor anyone else--can rightfully seize control of a woman's body without her consent.
Such relativism does not take into consideration firm and foundational moral truth - there are two persons involved in any pregnancy; the woman pregnant and the child. Both are living human beings. Both are developing, one more rapidly than the other. As living human beings, they both retain human rights, regardless of 'individual circumstances.' Too often have human rights been attacked under the guise of 'individual circumstances.' Torture could be justified by the 'circumstances.' Terrorism can be rationalized by the 'circumstances.' And yet, people constantly demand and call for moral integrity so that principles are not circumvented by the 'circumstances.' Circumstances are dynamic and constantly changing in our rapidly alternating environment. Moral truth, however, remains. And while there may be tension... human rights are not subject to the circumstances.
Presumably, the mother had an opportunity to abort the child while it was still in utero, so if she carried it to term, we can infer that she does indeed want to keep the child. If she then decides to neglect the child (or worse), then she has betrayed our trust that she will care for the child, and we can seek legal retribution. Note that in order for her to betray our trust in her, she has to have had the option of abortion to begin with, i.e. if she is denied the option of abortion, she has a legitimate reason to neglect the child.
Your first assumption, that the mother wanted to keep the child because she bore it full term, is just that, an assumption. She may have had to have borne the child because 'safe' abortion was not an available option for her. You do, however, suggest that it is 'legitimate' for her to neglect the child if safe abortion is not available. You do not provide any rationalization for such a position. And it is a matter of moral relativism again, that does little justice in considering the rights of the child, which are circumvented in this case, under the guise of circumstances again. What court of true justice would consider deliberate abuse 'legitimate' under the circumstance that the mother was not able to abuse the child prior to its birth?
The point I made earlier was to emphasize that it is considered 'moral' and even legally protected for a child to be neglected, abused and evicted from its first home in the world - the womb, and yet it considered immoral and illegal for a child to be neglected, abused and evicted from their homes after birth. You claim that the womb is the property of the woman, and she has superior right and authority to declare if she does not wish a child to be there that it must be evicted, via abortion. However, after a child is born, it lives in the home of its parents. That physical space is the property of its parents, and if the parents declare they no longer wish to share their property and resources with the child, are they not under the same logic entitled to evict the child from their property? It is, afterall, their property, is it not? And if they regard the child as an intruder, are they are not entitled to abuse it and evict it from
their property, since
their property rights are superior in authority to the rights of the vulnerable child?
A fetus is arguably harming the body of its mother during pregnancy. Other posters in other threads have listed the health problems that women often face during pregnancy--everything from fatigue to mental problems to diabetes to death during childbirth (this last fortunately being very rare, but it is still a possibility). The fetus most certainly does not have the right to inflict these problems on its mother if she does not want it to, and we most certainly do not have the right to force the mother to suffer from these problems. If the mother wishes to rid herself of these problems, that is her right.
For balance, perhaps you should also consider the protective factors involved in pregnancy, not merely the risk factors.
You claim that "the fetus most certainly does not have the right to inflict these problems on its mother." Pregnancy is a natural phenomenon. And all natural phenomena, including those of biology, involves risk factors. It is not the fetus that decides to inflict any such risk upon the mother, so why should the fetus be punished for something that it did not intend to cause?
And we return also, once more, to the discussion on property rights. If the woman can declare that her uterus is her property and violently evict her child from it, can a parent do the same to a born child, in the name of exercising their property rights? Under the same logic, they would be justified in doing so.
This argument can (and, indeed, has) been made for the purpose of discouraging every scientific advancement in the history of mankind. Every time someone makes a new discovery, there is always someone saying, "If we could control this naturally-ocurring thing, we would likely mess it up." Yes, the discovery of new phenomena and the utilization of new inventions is dangerous business, but the rewards are far greater: Every piece of modern technology we owe to someone's attempt to "control nature". You're staring at a piece of modern technology right now.
Scientific progress in not progress at all unless it is matched by progress in humanity's conscience and ethical understanding. What is the value in being able to control the very molecules of life and yet devaluing life as expendable at the same time? Our existence would be loose meaning and morality would be reduced to relativism where human rights are subject to circumstance and can be violated under rationalization of scientific progress. That is not progress at all, if advance scientifically and yet decline morally.
In the case of abortion, our attempts to "control nature" have resulted in the liberation of tens of millions of women who would otherwise have been chained to a baby they didn't want. I submit that humanity has benefited from such liberation. Women are our
friends.

(And no, humanity would
not have benefited from the addition of tens of millions of unwanted babies inflicting misery on unwilling parents.)
This ill-conceived 'liberation' has also enforced tyranny upon an entire generation of human beings, men and women, and has reduced them to the status of mere property. Human life in the womb has become legally disposable, as is property, and has thus been devalued. This 'liberation' has caused countless unborn child to scream silently for life that they will never be able to experience. It has subjected them to an invasive and violent death caused by unfeeling instruments that destructively violate their body's integrity. What kind of 'freedom' allows someone to kill another person in the name of choice? That is not freedom, but tyranny. Who benefits from such apparent 'liberation'? Certainly not the men and women who never had the freedom to live.