Why do people want to put a ban on abortion?

I'm not saying it okay not that i don't think its okay but i think it should be left up to the woman if she wants an abortion or not. I mean, teenagers are stupid. Its not their fault, hormones sometimes make them do crazy stuff. it just how humans ares during that age. And its not like it isn't natural for a male to want to have with a female at a teenager's age.. Just because its looked down upon in this society doesn't mean they should be forced to have the baby. Personally i believe that life begans after birth. And i don't think a child becomes mentally aware of what is going on until maybe 9 months after its birth. And i mean if you ban abortion than women will be going to underground illiegal abortion clinics and performing dangerous acts to create a miscarriage.