Interesting post. At least you've thought about the issue.
Now, to your point: what happens when the husband turns around and says, "we agreed to a non-reproductive marriage, and now you've unilaterally increased the stakes -- and your own legal rights vis-a-vis mine, not coincidentally -- by getting pregnant without my assent. You practiced to deceive me. Fraud!"
Also, if you simply say, "well, the State will take the children away from non-qualified parents," then what you've done is destroy an ageless right of people to reproduce, and made it a revocable license extended by the State in return for certain policy objectives being kowtowed to first. Such as (arguendo and ad absurdum, as an exercise in destructive testing of the idea) the right of the State to insist that parents agree to raise their children as Greenies or Democrats, in return for the license to bear children.
What about that?
Nuke Baltimore! That would solve the problem.
I think you'll be interested in my post 7.
Adoption.
Actually, your point isn't at all absurd. I give you the sixteen-year-old inner-city welfare child, gravita three, para two. It's been horrendously destructive.
The choice is ugly: either give the state the power to redistribute children to qualified households and watch those standards like a hawk, or allow the state to raise the children in a permanent majority underclass as we do today (in case anybody hasn't noticed). Personally, I would prefer to see the standards for marriage delegated to private charities carrying liability insurance by which to correct mistakes.
As I just posted on another thread:
By that time the educated parent is thirty-two. Her egg fertility has dropped in half. She will have a far higher incidence of birth defects. She will only have time for two, or at most three kids at a rational spacing. The only other option is to allow uneducated people to raise all the kids or import and educate new citizens. It's a recipe for demographic disaster.
This is why my home-educated kids were doing college level work before they became teenagers. Compressing the k-12 curriculum in math and history so that they could skip high school for college level technical and writing courses will have them so far ahead that they'll have time for a life that includes children.
We have a choice: an educated population of child-bearers on an advanced curve, a permanent underclass of breeders, or importing our future workers. It's time we faced reality.