The image of God
Mankind is unique in all of creation in being made in God's image (Genesis 1:26-27 and 5:1-2). This is true of the entire human species and of every member of it without exception, including unborn children. The sanctity that God's image bestows (even after the Fall) on each human being is affirmed by the prohibition on taking human life in Genesis 9:6. This prohibition became codified as the sixth commandment (Exodus 20:13). This is the fundamental pro-life position: that every human life is sacred.
Unborn children in the Bible
Because they too are made in God's image, unborn children are regarded in the Bible as having the same dignity as other human beings. Their formation and growth are said to be in the hands of God (Job 10:8-11) and it is possible for them to have a personal relationship with their Creator (Psalm 139:13-16). Jeremiah and Paul both received their calling from God before birth (Jeremiah 1:5 and Galatians 1:15), as does the Servant who was foretold by Isaiah (Isaiah 49:1-5). Samson was bound by vows as an unborn child (Judges 13:7) and John the Baptist was filled with the Holy Spirit (Luke 1:15) and displayed spiritual discernment (Luke 1:41-44) literally 'from the womb'. (Some versions - e.g. the New English Bible - translate this as 'from birth' which is unwarranted and, in the case of Luke 1:15, clearly wrong.)
The most important unborn baby in the Bible is Jesus. It is central to the Christian faith that the eternal Word of God took human flesh and lived a human life in this world (John 1:14). That life began at conception (Matthew 1:20-21). Luke describes how John the Baptist, as a six-month foetus, responded to the presence of Jesus as an embryo only a few days old (Luke 1:39-44). The human life of Jesus differed in nature from the rest of humanity's only in its sinlessness (Hebrews 4:15). Since his life began at conception, so does every human life.
The attitude that singles out disabled people for destruction (as seen in our abortion law) is very different from the Bible's. Like all other people, those who are disabled are made by God (Exodus 4:11-12). We have a common humanity (Job 31:15). They are not to be mistreated (Leviticus 19:14 and Deuteronomy 27:18), but on the contrary are to be granted justice (Psalm 82:3-4 and Proverbs 31:8-9). As Christians, we are to bear one another's burdens (Galatians 6:2) and may look forward to the lifting of all our disabilities (Isaiah 35:5-6).
Love in action
The parable of the Good Samaritan (Luke 10:29-37) bids us extend the limit of the neighbours we love beyond where it presently ends. In our own society it ends at the unborn child. Jesus announced his ministry as good news for the suffering (Luke 4:18-19) and his followers must do the same. There can be no pretending that what is happening to unborn children is in some way for the good (Isaiah 5:20), or pleading ignorance as an excuse for inaction (Proverbs 24:11-12).
ConclusionThe Bible clearly emphasises the sanctity of every human life, including the life of those in the womb. As Christians, we are bound to take a pro-life stance, and defend unborn children, whom God has made in his own image.