ANSWER: What the Bible does say about abortion has deeper spiritual consequences than society realizes. Each pregnancy is a miracle from God, made possible so that another human being has the potential of becoming one of his sons or daughters and inheriting eternal life. The real sin of this abominable practice of abortion is man's attempt to thwart God's plans for a large family.
Part of the human rationale for supporting abortion is that what is in the womb is NOT a person and that, since it is part of the woman's body, she has the sole right to make decisions about it. The truth is, however, that what is conceived is a new life unto itself. Conception brings together all the genetic instructions needed to create a unique, never-before-existed human being. All that is needed from this point forward is a safe and nurturing environment in which to grow. Abortion completely stops this natural growth process.
What grows within a woman when she becomes pregnant is a human life. According to God's word, the taking of that life through abortion is murder based on the sixth of the Ten Commandments (Exodus 20:13, Deuteronomy 5:17).
God inspired King David to recognize that his life began at conception when he caused him to write how "wonderfully made" he was in the womb. David attributes to GOD his creation as a human being, in the body of his mother, at least six times in Psalm 139:13 - 16. Scripture does speak of knowing a person even before they are created (see Jeremiah 1:5, Luke 1:13 - 17, 31 - 33).
Note the following in regard to the argument that an abortion does not kill a "real" person. After God miraculously caused the conception of Jesus in Mary's womb she travelled "with haste" to stay with Elizabeth (Luke 1:56), who was six months pregnant. When she arrived the baby inside Elizabeth, upon hearing Mary's voice, leaped with joy (Luke 1:41)! This tells us that a six-month old fetus not only detected a person who had been conceived just WEEKS earlier but also recognized their mother's voice AND responded accordingly! It would be ridiculous to think that Elizabeth's child was responding to just a "mass of tissue" inside Mary.
Abortion has been sadly practiced and justified by humans for a very long time. In fact, according to Roman law, even a newborn baby was legally not considered a person until the father accepted him or her as a family member (The IVP Bible Background Commentary, comments on 1Corinthians 7:1 - 7). Although taking the life of someone in the womb was widely practiced in antiquity, it was unanimously condemned by both Christians and Jews.
Simply put, abortion is man's deceived attempt to deny God a family through murder. Clearly, such behavior is not his perfect will. What grows inside a pregnant woman is a child, someone with a purpose in the Eternal's plan for all man. One has to wonder what things in the world would have been different if killing unborn babies was not an option. Human life does not begin at birth, but at the moment of conception when sperm and egg unite to form all the genetic instructions necessary to produce a human. The killing of babies God has formed in the womb, through abortion, is a sin.