And by the same reasoning the man didn't help create a child, they helped create a fetus. It is the mother's decision alone that led to the fetus becoming a child.

Now this isn't the only argument for abortion, but it is a common, rhetorically effective one. However it does mean that as long as women aren't aborting children, men aren't helping create them.

Other arguments for abortion include the right to body autonomy, in that women should not be forced to support another being, but since children require support after being born as well, that would extend to forcing to support them afterwards and by other means.

In essence, arguments for compulsory/non-consensual child support are basically arguments against abortion and vice versa. From a purely ethical standpoint there is a lack of consistency in the degree of choice into becoming a parent both aesthetically and legally.

If we are to allow abortion, then we should not have compulsory child support unless both parents have similar means in consenting to parenthood. This does not mean giving the father say over the woman's choice for abortion, but it does mean that a) the father has equal say in adoption/safe haven abandonment and b) the father can abdicate his responsibilities and rights within the window for abortion.

Equal responsibility with equal sovereignty. One without the other is unacceptable and often unsustainable.