Judge Upholds Death Sentence for Peterson

All over the news today I heard that Peterson is a monster for killing his wife Laci and her unborn child. "Unborn child"...Isn't that an oxymoron?
Peterson was sentenced to death for 1st degree murder and 2nd degree murder.
So if a woman or a doctor performs an abortion, it is not murder; If a mother puts herself at risk and loses the baby, it is not murder.
If Peterson is guilty of 2nd degree murder, why are abortions legal? It seems like a double standard to me.
It seems to me that one can't kill something that isn't born. But, if we can establish when life begins, then we can determine when ending that life becomes murder. If ending the life of a fetus is murder, we better start building more prisons (or gas chambers).