A) It is an established scientific fact that life begins at conception.
B) Even abortion advocates concede that abortion kills a human being.
Why have all the teaching texts and so many medical experts come to this same conclusion?
Because there are simple ways to measure whether something is alive and whether something is human.
If life doesn't start until there is conciousness then when does that mean? is a baby concious of its surrounding? and why cant a fetus/embryo be? it knows the mother's voice before it is born and its inntellegence is created in the womb. it is not simply a collection of cells, they are doing something.
After conception a human being exists. All embryology (the study of embryonic development) textbooks agree that a human being exists. Scientifically those that belong to the species homosapien are human beings. As the zygote/embryo/fetus belong to the species homosapien (they are not some alien species nor cats nor dogs) they are human. Next, are they alive, well a normal zygote/embryo/fetus fulfills the criteria for life. Abortion terminates that. The zygote/embryo/fetus did not do anything that would make him/her not innocent therefore yes, abortion kills an innocent life.
What else could it be? A beautiful, human life. To keep a child from growing...from living...is murder. From conception, all genes are present that undeniably square out every ounce of its being. It may be fragile, but that tiny heart has no less right to continue beating than our own.
It is a scientific fact that an abortion ends the life of the young organism that is aborted (in humans, a prenatal child). As we are all presumed innocent until we are proven guilty, an abortion is in fact the killing of an innocent life. We already have laws which make the unjust killing of a child in the womb a crime of murder (Laci and Conner's Law.) That law for now makes an exception for abortions. However, the child killed in an abortion is no less innocent than one that is killed or "murdered" under the law.
Heart beat starts between 6-12 weeks , abortion during & after that is killing a human , the body of the child is not the body of the woman , she does not own the baby's body , so she does not have the right to kill it , if a grown up woman doesn't want to take responsibility , then she should have been more careful & use birth control from the start!
When a woman is pregnant we all know she is having a human baby not another form of life. Science has proven the reality of life in the womb. I have worked with men and women who suffer greatly after an abortion. They know the truth in the depths of their being. I have also watch many of these wonderful people finally find healing and peace once they admit and begin the forgive themselves.
Of the most influential abortion advocacy groups in the world (NARAL) and once served as medical director for the largest abortion clinic in America. In 1974, he wrote an article for the New England Journal of Medicine in which he states: 
There is no longer serious doubt in my mind that human life exists within the womb from the very onset of pregnancy...
Some years later, he would reiterate: 
There is simply no doubt that even the early embryo is a human being. All its genetic coding and all its features are indisputably human. As to being, there is no doubt that it exists, is alive, is self-directed, and is not the the same being as the mother–and is therefore a unified whole.
Don't miss the significance of these acknowledgements. Prominent defenders of abortion rights publicly admit that abortion kills human beings. They are not saying that abortion is morally defensible because it doesn't kill a distinct human entity. They are admitting that abortion does kill a distinct human entity, but argue it is morally defensible anyway.
We'll get to their arguments later, but the point here is this: There is simply no debate among honest, informed people that abortion kills distinctly human beings.
The problem is, Roe vs. Wade, the landmark 1973 verdict which legalized abortion in the U.S. is actually built on the claim that there's no way to say for certain whether or not abortion kills because no one can say for certain when life begins. Justice Harry Blackmun, who authored the majority opinion wrote: 
The judiciary, at this point in the development of man's knowledge, is not in a position to... Resolve the difficult question of when life begins... Since those trained in the respective disciplines of medicine, philosophy, and theology are unable to arrive at any consensus.
Justice Blackmun's assertion is a ridiculous one, at least as it applies to the field of medicine. Dr. Nathanson had this to say about the ruling: 
Of course, I was pleased with Justice Harry Blackmun's abortion decisions, which were an unbelievably sweeping triumph for our cause, far broader than our 1970 victory in New York or the advances since then. I was pleased with Blackmun's conclusions, that is. I could not plumb the ethical or medical reasoning that had produced the conclusions. Our final victory had been propped up on a misreading of obstetrics, gynecology, and embryology, and that's a dangerous way to win.
Dr. Nathanson would eventually abandon his support for elective abortion and note that: 
The basics [of prenatal development] were well-known to human embryology at the time the U.S. Supreme Court issued its 1973 rulings, even though the rulings made no use of them.
It is a functioning member of the species homo sapiens. That is what a living human being is. You do not get to kill a human being just because "Ohhhh I don't consider them human beings." Being a human being, a member of the species homo sapiens, is not a matter of opinion. It is a scientific fact. If it was just a matter of opinion, then there would be nothing wrong with what the Nazis did, since they didn't consider Jewish people to be human beings. Also, they are functioning member of a species, which is literally a category of LIVING things.
One more thing. There are only two kinds of people that I have ever seen comparing a group of human beings to parasites to justify killing them: Pro-choicers, and Adolf Hitler. If a "right to choose" you support depends on denying basic biology and denying that a group of human beings have any rights at all, then it was never a right in the first place, and you are on the wrong side of history.
Lets not pretend humans have any difficulty in killing innocent lives, we kill innocents in another country because we don't like how they rule, we kill innocents because we disagree with them, we kill BILLIONS of innocent living animals because we like it, so while yes abortion by definition is ending a innocent life we humans clearly are not above it.
Just like a caterpillar turning into a butterfly, a fetus turns into a human. It is not a human until it leaves the mother. A fetus is not the same as a child, since a child is only indirectly dependent on the mother, unlike the fetus, which literally shares her blood.
It depends on the stage of development of the fetus/embryo.
There are a few possibilities when life begins. All of you who state "life begins at conception" state it with conviction. But what scientific reasoning backs your claim? Consider these timepoints in the developmental phase when life could potentially start.
1) Conception (genetic)
2) After twinning is no longer possible (embryologic: about 14 days into development)
3) Brainwave criteria (neurological: about 24-27 weeks into development)
4) At or near birth (measured by fetal viability outside of the body)
I think criteria 3 makes the most sense.
Abortions are medical procedures performed on the female uterus. If an abortion is killing an innocent human life, then there are hundreds of thousands of murderers on the loose. An abortion is a woman's choice. In today's male-dominated society, the right to choose is just as sacred as the right to life.
Let's put abortion onto a scale. A 1 is a bacterium, something we kill every time we wash our hands; a 2 is a fly, something that has a super-basic nervous system; a 3 is a sewer rat, which has a specialized and highly focused brain; a 4 is a dolphin, extremely smart but still not conscious; a 5 is a human being, the only (remaining) animal on earth capable of rational thought. Where does a fetus fall on this scale, especially during various points during pregnancy?
Higher brain function doesn't develop until the third trimester, even anti-choice activists admit this. Sometimes they say that "abortion stops a beating heart," but flies and rats and dolphins have cardiovascular systems yet we don't consider that murder. So where does a fetus fall on the scale?
First trimester: somewhere between a 1 and a 2 (an embryo is literally just a mass of cells; only a tiny portion of the population believes this to be a full human being).
Second semester: somewhere between a 2 and a 4.
Third trimester: somewhere between a 3 and 5.
So even if you think late-term abortions (third trimester) should be illegal, which is a somewhat defensible position, there is simply no arguing that abortion a fetus at, say, 6 weeks is any more immoral than killing a rat. Obviously killing anything isn't a good thing (including rats) but if I killed one, it wouldn't keep me up for days.
Even by the second semester, at worst it's like killing the moral equivalent of a dolphin, which is a huge sport in Japan. Now I think dolphin killing is wrong because they are so smart; but should one think it is the equivalent of killing a full human being? Of course not.
So there you have it. The best argument abortion opponents have, that it's killing a person, is simply not true if you are a rational person. Their best point, that late-term abortions are bad, is moot: third trimester abortions are already illegal except when saving the life of the woman.
Therefore be it resolved, abortion should be legal in most or all cases.
I believe that life cannot truly start until the being is conscious of itself and its environment. An abortion, if performed early enough, would not be killing an innocent life but would simply be killing some cells. If that is considered an innocent life then every time someone cut themselves they are killing an innocent life, how absurd. An abortion simply kills cells before they have had the chance to form into a new human being.
Abortion doesn't kill an innocent life, it ends something before it has had the chance to develop life. It prevents babies from coming into the world and living a life where they will possibly be abused and unwanted or live out their time in dirty, crowded foster homes. Late term abortions are not legal because that is where it becomes a murder, an embryo is not a human life and should not be considered as such.
When an abortion takes place, I do not believe that the fetus is developed enough to be considered a human being. It is not "murder" because the fetus does not feel, think, and make its own decisions. Some people argue that you are ending the possibility of a life, but A) America is overpopulated, schools are overcrowded, and the environment is becoming less and less healthy because of the huge population, so adding another life can be unhealthy to the baby B) It is much more humane to have the fetus aborted before it develops into a human rather than have the baby be abandoned or put up for adoption because the parents can not take care of it. By refusing to abort this unwanted fetus, you are pushing away existing children's chances of being adopted. How is it fair to the baby to never know it's parents? How is it fair for a child to be born and abandoned? Wouldn't you rather a child be raised in a healthy, loving home? Obviously not, since all that matters is that the child is born, even if it is unwanted and will probably be abandoned or unloved after it is born. C) It is unfair to the MOTHER. She should not be forced to give birth and raise a child that she does not want. She has more rights than the fetus in her stomach. Perhaps you should think of the existing human being rather than the possibility of a human being in her stomach. If a woman is raped, it was not her choice to become pregnant. A baby can completely ruin someone's life, especially if they are still in school.
Woman should be allowed to make the decision on whether or not a life can realistically be brought into this world. Alot of circumstance prove otherwise, rape incest financially unstable . We dont know the struggles of others, so why is it our business. Its a collection of cells, not fetus
Since abortions are typically done during the early stages of pregnancy, in my opinion the fetus has not matured enough to consider it a living person. I think late term abortions are questionable in regards to this, and should only be performed in cases where it poses serious risks to the pregnant woman.
There's no real way to put it other than "abortion is not murder". It is a clump of cells. It has a potential to become a human but if a woman chooses to, she should be allowed to end an unwanted pregnancy without fear of judgment or negative repercussions. It is her body. Her right to choose.