In a nation that prides itself on how well children *must* be treated, both by law and by social pressure, the birthrate drops like a rock.
... but I see it in action in my area! We have the most crowded house - 2 adults, 8 children, 2 gerbils and a fish - of any family in our subdivision of 280 houses. And this is a neighborhood that includes Mexican, South American, Russian, and African immigrants.
I know our sleeping arrangements are against "child welfare" rules, in fact, because I have a baby in a crib in my closet!
On the other hand, there was no government subsidy to reproduce in my great-grandparents' time, and much less "drag" on families overall. My approach overall would be to eliminate as much government influence from every area of life (unintended consequences!) as possible, rather than having government deliberately act to increase birth rates. You can assume, as a generalization, that if government tries to produce result "X", you're going to end up with Q, R, and Z, but not X!
Granted, government does muck up things royally, as a rule. But there is also social pressure that is applied to young couples that makes having children much more difficult--and is far less controllable.
That is why such a radical step as a new city in the first place. To make a place with not only everything conducive to having children, but the absence of things that interfere with reproduction. And this can be an odd blend.
Great OB/GYN services, except with no birth control or abortion. Medical exams, even fertility exams before residency. No old people, adult singles who don't want to be married or have kids, homosexuals, genetic diseases, psychological problems, it's a long list of exclusions.
Employment has to be 100% for males, with only home-based businesses available for women. For the men, it is dreary and boring cubicle or retail work, and for women, it is boring housewifery.
The government will have to viciously fight off organizations and individuals who would do anything to get into such a situation for their own benefit. Young families are prime targets for any number of scoundrels and businesses that wish to exploit them.
So what is the end result? Families with no credit, but a good nest egg of cash, yet nothing to spend it on. Feeling very secure, but bored. Comfortable but not materialistic. Not able to travel much out of their city.
This is inherently a very odd place, and much like some parts of the US in 1950s suburbia. To call it a major, national project is an understatement.