The book of Amos primarily contains prophecies and judgments pertaining to Israel. But the book begins by listing various sins of the surrounding cities and nations, finally ending with Israel.
The words condemning each place begin with this phrase: "For three transgressions...and for four I will not revoke its punishment" (Amos 1:3,6,9,11,13; 2:1,4,6). Most of the time, this phrase was followed by just one sin. The phrase is a figure of speech meaning that this sin that is mentioned, after everything else they had done, is what caused the Lord's patience to end and His wrath to begin. Each city or nation reached this point in different ways.
Notice in particular the words regarding Ammon:
"For three transgressions of the sons of Ammon and for four I will not revoke its punishment, because they ripped open the pregnant women of Gilead in order to enlarge their borders" (Amos 1:13).
What did the people of Ammon do that caused the Lord decide it was time to punish them? They killed the unborn children.
We see the attitude of the Lord towards those who would have no regard for an unborn child and choose to abort a baby. Those who practice this, and those who defend the practice (cf. Romans 1:32), must repent if they want to avoid God's punishment. And the punishment that is coming is far worse than what Ammon was threatened with (Matthew 13:50; Mark 9:48; Revelation 21:8).
Every soul is precious to God. That is why He sent Jesus to die for all (John 3:16). God is also "not one to show partiality" (Acts 10:34), which means that the soul of the unborn is just as precious to Him as the soul of the born.
The word of God uses the same Greek term (brefos) to describe a child inside the womb (Luke 1:41) and outside the womb (Luke 2:12). This is different than people today who call an unborn child an embryo, or a fetus, but not a baby.
We must see the unborn as God sees them -- human beings, living beings, that are precious in His eyes. They must not be disregarded. They must not be downgraded to something less than human, and therefore, can be eliminated. God will deal harshly, and justly, with those who practice or defend this type of infanticide.