It's easy to judge others when we have everything (ok, maybe not everything, but at least the bare minimum) to lead a decent life. =/ Do remember that this is a work of fiction and like she said, she IS poor. So contraception? You think she could afford the pill? You and I have both seen how it goes in hentai, right? Well, think of it like a hentai story gone wrong.
She was working as a sex worker, par of it is using contraception not just to avoid pregnancies but also STD's, charging for extra services like unprotected sex implies taking into account the cost for things like a morning after pill
But lets say she was reaaaaaaaaaally strapped in for money, and didn't do any of that, and the universe bend over and spared her for catching any bugs and ending pregnant was the worst of it
She still decided to carry on with the pregnancy, lets chunk it out to monetary problems
She still decided to keep the child with her and neglect it, instead of giving her up for adoption
And that has no excuses, that's not a problem of money, that's her just going out of her way to chain an unwanted kid and making them suffer innecesarily
From conception till now, she had, for every day of that girls life, the option to just free the girl from being under her legal care, but she opted to instead just left her to die abandoned in an apartment
That's not a problem about being poor, she is just an asshole