If a woman has sex, even when using birth control, and becomes pregnant, how did she not consent to the risk of pregnancy? As I submit that she did, how is she therefore not responsible for the child?
You have already conceded that birth control is not 100% effective. You know this from the packaging and/or doctors. As such, you realize that you're taking a risk. Sure, a very slight risk, but a risk nonetheless.
By saying that you never wanted this, how does that make you not responsible? You consented, even if you don't want to admit it. You know that the possibility exists, you're taking the chance, if you get "unlucky" and become pregnant, you're not less responsible than if you hadn't taken the contraceptive.
I challenge you, please, show the errors of my argument. But do so with facts, logic, and/or reasoning, not opinions. I will call you on all opinions, so don't be surprised about this.