Abortion in most countries in the world is still legal under the grounds that a woman has a right to control her own body - whether she wishes to carry a fetus in her own body or have it removed. Most abortion opponents consider these grounds for legalizing abortion to be invalid and that abortion as sinful - the same as murder. Though it may not be obvious to abortion opponents - nobody is pro-abortion. Everyone is against abortion although many support the right of woman to make her own decision about it. (I support the right of anyone not to take a shower or not to wear clean clothes - but I am definitely not pro-dirt).
For anti-abortion people aborting a fetus or taking the life of the unborn person, is the same as taking the life of a living human being (Most of them however, have no problem with the death penalty or the deaths of thousands of innocents caused by a war which they support - they somehow do not see the contradiction).
The question is - Is the unborn fetus a human being?
In 1869, the Catholic Church under Pope Pius IX declared that the 'ensoulment' of the fetus occurred at conception, essential the soul fused with the single fertilized cell at conception to become a 'human' being. (Pope Pius IX was also the one who clearly established the principle of papal 'infallibility'). Before 1869, the time at which 'ensoulment' took place was debated, but never considered to be at conception. Thomas Aquinas, for instance, believed that ensoulment occurred 40 days after conception for males and 90 days after conception for females. Jewish Talmudic scholars claim that ensoulment takes place once a human form is established 40 days or more after conception. Buddhists have a similar belief, while the Koran specifies 120 days after conception. Whatever the exact period, it should be obvious to rational people that the soul would not want to enter the fetus until at least the fetus had a heart that was beating and the semblance of a human form. After all, the cells before conception - the unfertilized egg, the millions of sperm are 'living' cells too! Apparently for those who are blinded by fanaticism or ideology or even blinded by hate for the so-called 'pro-abortionists', this fact is not so obvious. Such hate is definitely un-Christian.
According, to my own information, the soul enters the fetus only sometime after the heart starts beating (not necessarily at the exact moment) and a semblance of a human form is developed. However, after that instant, the soul does not remain there (being inside someone's womb continuously for several months is too confining for the soul). The soul enters and leaves the fetus periodically after that, basically just trying to get accustomed to being inside a physical body. It may spend considerable time in the fetus depending on how much it can tolerate the confinement. Only at the time of birth, does the soul get completely fused with the body. However, that does not mean that abortion at any time during pregnancy is without any consequences. All abortions are an act of karma, which the perpetrators - the consenting mother/father as well the performing physician earn. This karma gets accumulated with their existing karma. In some cases, where the fetus is deformed or diseased, it may actually result in good karma for the physician and neutral for the mother/father. In other cases, it may be just a mild addition to their karma (we earn bad karma just by calling people names like murderer).
In no case, however, is it the same as taking a human life. There is no separate human life until the fetus can survive on its own outside the mother's body as a normal baby (with the help of an incubator, if needed). Abortion in many cases may be a preferable option to bringing an unwanted baby into this world. In many cases, abortion does add to the bad karma of the people involved (which they will have to pay for in the future), but in no case is it the same as murder. People who harass or threaten those who participate in performing abortions probably earn far worse karma.
This debate in the US has now become so heated that we can no longer seem to talk about it as reasonable people. Jesus was far more compassionate and liberal than the so-called 'pro-life' advocates. The only way this will get resolved is with the actual Return of the Christ and that is actually scheduled to happen quite soon.