To add to the economic deterrent for having children, there is also a biological aspect to population density rates. At some point when the population density rises, the birth rate drops because fertility rates drop. This was proven with mice decades ago and now there are scientists wondering if we are finally seeing the effect duplicated with humans.
While its a problem with sustaining any country's GNP as the labor force ages, its good to have the population increase slowed.
I still support ZPG (Zero Population Growth), just not through abstinence
or genocide
.