In the event you get her pregnant, I think you'll find there are, in fact, guarantees.
But there shouldn't be.
It is unjust and against nature--and human nature--for the law to enforce such an obligation without the man and woman having first legally married.
Marriage is a contract that exists to protect women should they become pregnant.
No no legal obligation should ensue to the man who is not a woman's husband.
Otherwise, the woman is having it both ways.
That a woman is the one to become pregnant confers on the women evolutionary advantages (the baby always carries her genes).
But she pays for that advange--as is fair--with a price: She can have only one baby every year or so.
Therefore it would likely be woman's evolved nature to desire sex with a man who will endow her child with good genes, and with a man she can be sure will be around to help her bear and raise that child.
She should therefore evolve emotions to lead her in such direction.
Men, on the other hand, do not get pregnant. Which is an advantage as they are BY NATURE FREE to make as many babies as they can find women to impregnate.
But nature is fair and makes men PAY FOR THAT FREEDOM by a man's never being sure any baby he thinks he's made is really his.
So the checks and balances are already in us.
For government to force men to pay for babies made out of wedlock, is giving the female of the species all the advantages.
And it also destroys the need for marriage, as we now can substitute DNA testing and lawyers instead.
And for a man to betray his sex, by adding legal advantage to woman's biological advantage, is folly.
And is evidence of the success of liberal social brainwashing.