It's been proven beyond all doubt for decades that high prison sentences are not a deterrent to crime, we know that from statistical analysis and psychological research. Giving this woman life imprisonment would not stop anyone else doing what she did.
These threads would be so much shorter if people just admitted they're only interested in vengeance instead of dressing it up in fake concerns for justice or preventing future crime.
She let a baby die, you want her punished harshly enough to make you feel better, that's it.