Goodness me.
Awful, awful story - poor baby.
Supported living in this context implies a shortfall in the support IMO. If it was a hands off approach, with occasional CCTV checks for example, how come at the very minimum it wasn't noticed that the mother left her home without baby and did not return for 6 days? If no-one else was coming or going surely after 24 hours someone would have done some sort of check.
Speculating on her motivations is useless - as others have said, we are not privy to all the facts, and may never be.
For those opining that such people are psychopaths with no hope of reform who should be preferably lynched, may I remind you of the case of Mary Bell?
It's an emotive subject for sure, but clinging to medieval concepts of irredeemable evil and the consistently perfectly and good responsible kind of undermines the decades of research that shows how much environmental impact on mental development influences behaviour later down the line. To use a common Mumsnet "excuse" our brains don't finish developing until we're 25, and the last bit of consolidation is around risk taking behaviours. Which is why lots of nightmare teens are fairly responsible and thoughtful members of the community as they MATURE.
So yes, it's utterly awful, and no, there are no "excuses" but their may be clearly evident reasons, which we are not aware of for this situation. If the CPS had enough evidence for murder, that would have been the charge. If they don't, despite what some would desire, she has a right, as we all do, to a full examination of the circumstances before sentencing, without gender / sex related prejudice which to be frank I am seeing here. Our legal system already demonstrates a bias towards men committing violence or CSA as being "under stress" "just snapped" "such a good husband / father yadda yadda yaddad" even when some evidence absolutely shows otherwise.
It's got to be a fair system for all.
Denial is a strong theme in people who can't face their guilt, it has to be worked through, and no, not pandered to.
We've all got the capacity to choose good over evil, but it's very shortsighted to assume that we would never ever make a particular bad choice in certain contexts.