I just realised something.
She didn't want the baby.
Well, yes of course, she didn't want the baby, she let it to die in the car, but listen to me.
She didn't want a baby.
So she most likely tried to abort.
Imagine, after taking the next day pill. Dead egg come out, but she still feel morning sickness. An other test and she realises she is still pregnant and almost kill herself keeping eating those pills. Still pregnant.
So after a while, she goes to planet parenthood, a bit freaked freaked out that a dead litter of dead bloody eggs already came out of her vagina and yet there is still something in her. she is hoping this time she can get rid of it And right after it is removed, it pop up back into her womb kicking. She totally freak out, she leave and try going from an abortion clinic to an other but the little fucker will keep re-materializing in her womb no matter the amount of dead little babies that come out of it.
So, of course, when it finally get born, she totally want to get rid of that freakish abomination that has turned the last 9 moonths of her life in a nightmare. And thus he is abandoned.