In Jeremiah chapter 1 God SPEAKS to Jeremiah in his Mother's Womb.
Psalm 51:5 "Behold, I was shapen in iniquity, and in sin did my mother conceive me." David is saying he was Sinful at Conception, you can only be Sinful if your alive, but more then that, Sin is unique to Human life, Animals are never defined as Sinning Biblically even at their most animalistic. Some will try to argue this refers to Sex, that is idiotic, I've written entire articles elsewhere on how that's not how the Bible views Sex, but either way Psalm 51 is David talking about HIS Sin.
Abortion as an intentional act is specifically mentioned only once. Amos 1:13 "Thus saith YHWH; For three transgressions of the children of Ammon, and for four, I will not turn away the punishment thereof; because they have ripped
Genesis 16:11 "And the angel of the LORD said unto her, Behold, thou art with child, and shalt bear a son" Not Fetus not Zygote but Child.
Exodus 21:22-23, isn't entirely
Psalm 139:13-16 actually describes the Conception process, with amazing Scientific accuracy for over 3000 years ago.
Isaiah 44:2&24 also clearly refer to conception.
We know from Genesis 9:4-6, Leviticus 17:11&14, and Deuteronomy 12:23 that "The Blood is the Life" and that the Shedding of Man's Blood is murder. Genesis 4 also bares this out. The "Fetus" has a Heartbeat at 21-24 days, before most women ever know their Pregnant.
Let's look at the New Testament.
Like 1:15 "and he shall be filled with the Holy Ghost, even from his mother's womb." Luke 1:41- "And it came to pass, that, when Elisabeth heard the salutation of Mary, the babe leaped in her womb; and Elisabeth was filled with the Holy Ghost: And she spake out with a loud voice, and said, Blessed art thou among women, and blessed is the fruit of thy womb. And whence is this to me, that the mother of my Lord should come to me? For, lo, as soon as the voice of thy salutation sounded in mine ears, the babe leaped in my womb for joy." Remember that if your ever quizzed on when the Ministry of John The Baptist began.
Life ultimately can't be defined purely Scientifically "A live body and a dead body contain the same number of particles. Structurally, there’s no discernible difference. Life and death are unquantifiable abstracts. Why should I be concerned?"-Dr. Manhattan.
Lots of people have been declared "Legally dead" because their heart stopped but been revived. And some people can even be declared "Brain Dead" but other parts of their bodies still function. So if the end of life can be as ambiguous as it's start. Yet many Pro-Choice people will call you an Idiot if you choose to define life as beginning for example even as soon as it's Heart Beats. The most common argument is "Viability" well lots of born individuals lack "viability".
Problem exist even when defining the beginning of life Metaphysically or spiritually. It's often worded as a matter of when the Soul enters the Body/Fetus/Zygote or whatever you call it. But you see The Bible does not support the idea of Pre-Existence, though it's part of many apostasies.
Genesis 2:7 "And Yahweh God formed Adam of the dust of the ground, and breathed into his nostrils the breath of life; and Adam became a living soul." Doesn't say a Soul entered him, it says he "became a living soul". I don't believe it's only the body created at conception, I believe the soul and spirit are as well.
Conception is a process that begins when the sperm enters the egg, not merely a "moment". A process which as I said early on here The bible describes in detail, the "Zygote" may not be "a living soul" when the process begins, but it is by the end I believe.
One fact that is no common knowledge is that the sperm usually doesn't reach the egg till over 12 hours after ejaculation. This ignorance is why the "morning after pill" is often incorrectly defined as a type of abortion. There is an Abortion pill now, but it's a very separate pill.
The morning after pill is merely a sort of concentrated birth control pill, (which women are told not to take if their already on the pill). It will not harm an already conceived "zygote", it merely attempts to prevent conception from happening. It's not the same as Abortion and whether you view birth control itself as wrong or not it can't be called murder, and so as a Libertarian I certainly don't want the morning after pill to be illegal.
Defining when life begins is not the only issue with regards to Abortion. I have a post on the Politics and Religion forum dealing with that more.