She was 14 when she got pregnant. Legally, that's a rape. Being able to conceal a full term pregnancy almost guarantees that there's significant dysfunction, for family denial or for noone to really notice. To give birth alone and in total silence to a larger than average baby would be beyond most adult women, let alone a teenager. Something was terribly wrong.
What she did was awful. It's also awful that she's getting a sentence far harsher than people who do so much worse, without the vulnerabilities. From a societal level, this is unlikely to be a meaningful deterrent, and all we are doing is paying huge amounts to lock up a vulnerable teenager for long enough to ensure she comes out more damaged and likely more dangerous. Nobody wins here.