The responsibility is on, first, the attacker. You are attempting an argument no one is making and appealing strictly to emotion, [@Penny]. Second, the victim does have options beyond that if they are subject to sexual assault; an unwanted pregnancy is not an assured, guaranteed outcome. Failing to take up on those is a decision made by that person, who can weigh it only for themselves. This is one of the areas, as I stated but you apparently willfully ignored, there might be an argument for an abortion. Not only is it limited in scope, the victims in question have a valid claim, not just "Something, something, economic burden." or "I made a mistake."

People do not actually have as much "control" over their lives as they pretend to. They can mitigate threats and reduce them, eliminating some, but never them all. Putting all the authority into the hands of one person, especially who has direct charge over life and the welfare of it, should come with tremendous consequence for willful negligence. [i]Most[/i] receiving these practices are not victims of rape or under threat for their own life, which should be mentioned. It is used as a flimsy excuse to send some message about "control over their own body". 

You know what constitutes superior control over one's body? Not going to bed with a man and ignoring tenants of safe sex. A woman who cannot do this is less a woman and more a girl, because it is clear they cannot be held to the standards of an adult. I should also mention any man not willing to parent the child he fathered is a mostly spineless thing too; a boy pretending. At such a point if they err that badly, or "miscalculate" who they are involving themselves with or their life planning, no one should be at fault but them. The child should not be given the axe just because two adults spectacularly failed.

Additionally, there is no loss of rights or autonomy involved when the person in question neglected to maintain control over them. They surrendered them upon the altar of inaction as choosing to do nothing about it to prevent it is still a choice. At that point they are responsible for more than themselves; sacrificing someone else's life so to not hamper their own is not only cowardly, it is not an acceptable thing to do.

As for being "ethical solution", that is an opinion, not a fact.