Is it really a sin?

It is very likely that I am missing some Bible passage somewhere that touches more on this subject. I am by no means an expert. If you are reading this and you know of something- please let me know.

Did you know that no where in The Bible does it say anything about abortion being murder? The only thing it says about the subject is that it is a sin for a man to hit a woman who is pregnant and cause her to have a miscarriage, and that this is less of a sin than murder. So if The Bible doesn't consider a forced miscarriage murder, then would that conclude that abortion (which is basically a forced miscarriage) isn't murder either? Let me be clear, I am not stating what my opinion is- I just want to open it for discussion.