This is a case where it isn't sexist to take sex into account. Sorry, men, the woman has the pregnancy as a body part, and you don't, so you have no say about what happens to the pregnancy. Even if you both were protected and conception is accidental, sorry, it's up to the woman whether to stay pregnant, and up to both of you to support the child after birth if that is what happens. No opting out unless giving up for adoption.
However: I don't see why a man, who accidentally gets a woman pregnant, can't opt for adoption too, and give the financial responsibility to someone who wants it.